Upload
nguyendang
View
216
Download
0
Embed Size (px)
Citation preview
Hindawi Publishing CorporationAdvances in Power ElectronicsVolume 2013 Article ID 719847 10 pageshttpdxdoiorg1011552013719847
Research ArticleDevelopment of a New Research Platform for Electrical DriveSystem Modelling for Real-Time Digital Simulation Applications
S Umashankar1 Mandar Bhalekar1 Surabhi Chandra1
D Vijayakumar1 and D P Kothari2
1 School of Electrical Engineering VIT University Vellore 632014 India2MVSR Engineering College Nadergul Hyderabad 501510 India
Correspondence should be addressed to S Umashankar shankarumsgmailcom
Received 31 January 2013 Revised 1 June 2013 Accepted 29 June 2013
Academic Editor Don Mahinda Vilathgamuwa
Copyright copy 2013 S Umashankar et alThis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
This paper presents the research platform for real-time digital simulation applications which replaces the requirement for full-scaleor partial-scale validation of physical systems To illustrate this a three-phaseAC-DC-AC converter topology has been used consistsof diode rectifier DC link and an IGBT inverter with inductive load In this topology rectifier as well as inverter decoupled andsolved separately using decoupled method which results in the reduced order system so that it is easy to solve the state equationThis method utilizes an analytical approach to formulate the state equations and interpolation methods have been implemented torectify the zero-crossing errors with fixed step size of 100 120583sec is usedThe proposed algorithm and the model have been validatedusing MATLAB simulation as m-file program and also in real-time DSP controller domain The performance of the real-timesystem model is evaluated based on accuracy zero crossing and step size
1 Introduction
The ever growing complexity and size of electric drives andtheir related mechanical loads [1] represent an importantchallenge for those responsible for their testing and verifi-cation The considerations highlight the need for a thoroughand exhaustive testing of the controls under conditions thatare realistic [2] For these reasons it is customary thatall controllers for high-power electric drives be tested incontrolled laboratory conditions [2]
A recent alternative way of testing that is fast becomingquite popular is to use fully real-time digital simulationThesesimulations can also be interfaced with industrial controllersthus saving a lot of the investment cost and allowing aneconomic tool for drive controller testing and offering theflexibility needed to simulate machines in all power ranges[2]Theuse of virtual system enables relatively easier interfaceof the drive systems to the computer and it allows fasterldquoonline data and signal processing for analysis purposesrdquoEarlier hardware has been replaced by equivalent simulationmodel and the same has been tested using controller the
so-called HIL Recently systems tested in real time fullydigital simulation with controller as well as hardware usinga simulation model [3]
Simulating a drive in real time starts with the problem ofmodelling the drive and various works have been made indeveloping models of drives most notably those in [1 2 4]The authors of [4] have proposed an interesting alternative tomodelling the drives using a state-spacemodel that can easilybe implemented using MATLAB and the parameters can befound from standard theories and tests [4] Many researchersare doing this research work and found various approximateand optimistic solution approach methods and tested thesame Based on their past experience a simple method toform state equations involves switching function method [5]This method involves mathematical modelling of a systemrather than a circuit-basedmodeling and hence does not havethe problemsmentioned like in PSpice PSIM [5ndash7] Also thismethod is defined by its function related to its state ratherthan its generalized equation But coupled method suffersfrom numerical error due to higher order system equationsSo in this work decoupled method is used which is very
2 Advances in Power Electronics
sim
Inductionmotor
sim
sim
IREC IINV
IDC
Vdc
Vsa
VsbVsc
D1 T D2 T D3 T
D1 B D2 B D3 B
TU1 TU2 TU3
TL1 TL2 TL3
Du1 Du2 Du3
Dl1 Dl2 Dl3
Figure 1 Three-phase converter topology with diode rectifier DC link and inverter fed IM
simVdc
sim
sim
D1 T D2 T D3 T
D1 B D2 B D3 B
Vsa
Vsb
Vsc
(a)
+minus
+minus
Inductionmotor
Vdc2
0
Vdc2
TU1 TU2 TU3
TL1 TL2 TL3
Du1 Du2 Du3
Dl1 Dl2 Dl3
(b)
Figure 2 (a) Circuit 1 diode rectifier with DC link (b) Circuit 2 inverter fed induction motor with DC source
simple and allows developing the analytical equations suitablefor any power electronic system by decoupling rectifier andinverter This also gives exact solution and error is almostreduced
In this paper decoupled method for a simple three-phaseDC link inverter fed induction machine is proposed Thetopology of the converter considered in this paper comprisesdiode rectifier capacitive DC link PWM IGBT inverterand induction motor as load Decoupled analytical methodis used to solve all the state variables of the earlier testcircuit (source current DC link voltage and load current)for accurate results Decoupling is implemented to reducethe system equation order so as to achieve fast calculationand easier to get an analytical expression from solution tostate-space equations of the two converters Performanceparameters of the drive system have been validated usingMATLAB scripts (m-file) and also on DSP platform Thismethod has advantages like reduced system order simplifiedsolution easier calculation exact zero crossing and less datastorage due to large step size comparing coupled method
2 Methodology
Figure 1 represents the topology of the power converter tobe modelled with decoupled algorithm with zero crossingIn every sampling period of the discrete model two circuitsare considered The first part of the circuit consists of an AC
voltage source having an internal impedance connected to adiode rectifier with a DC link capacitor The second part ishaving a constant voltage source in DC link PWM inverterand an IM load At the end of every sampling period DC linkvoltage is computed by integrating the difference in rectifierand inverter currents
The proposed decoupled algorithm to solve the state-space equation of the electric drive system is given later
Step 1 Initialization parameters of the selected system
Step 2 Decouple the diode bridge rectifier and inverter fedinduction motor circuit
Step 3 Define different cases with an equivalent circuit fortwo decoupled circuits
Step 4 Assume that 119881dc0 is a known value (initial value = 0)
Step 5 Solve state-space equation of the diode bridgerectifier and find rectifier side DC link current (119868REC)
using analyticalnumerical method based on its switchingstatesfunction
Step 6 Solve state-space equation of inverter fed induc-tion motor and find inverter side DC links current (119868INV)
using analyticalnumerical method based on its switchingstatesfunction (see Figure 2)
Advances in Power Electronics 3
PU
Va
Vb
Vc
+minus
+minus
0Vdc2
Vdc2
N
sim
sim
sim
Ea
Eb
Ec
Lla
Llb
Llc
Rla
Rlb
Rlc
PL
TU1 TU2 TU3Du1 Du2 Du3
TL1 TL2 TL3Dl1 Dl2 Dl3
Figure 3 IGBT-diode inverter circuit with equivalent inductionmotor
Step 7 Find capacitor current 119868DC119899+1
using rectifier andinverter side DC link currents from Steps 5 and 6 respec-tively
Step 8 Solve the differential equation of DC link current andfind 119881DC
119899+1
using analyticalnumerical method
Step 9 Repeat the iteration for all cases up to stop time
Step 10 Compare with offline simulation results usingSimulinkSimulation tool
119868REC119899+1
= ((05 lowast (1 + sign (119868119886119904119899+1
) lowast 119868119886119904119899+1
)
+ (05 lowast (1 + sign (119868119887119904119899+1
)) lowast 119868119887119904119899+1
)
+ (05 lowast (1 + sign (119868119888119904119899+1
)) lowast 119868119888119904119899+1
)))
(1)
119868INV119899+1
= 05 lowast ((1198681198791198801
+ 1198681198631198801
) minus (1198681198791198711
+ 1198681198631198711
)
+ (1198681198791198802
+ 1198681198631198802
) minus (1198681198791198712
+ 1198681198631198712
)
+ (1198681198791198803
+ 1198681198631198803
) minus (1198681198791198713
+ 1198681198631198713
))
(2)
The equation for diode rectifier side DC link currentcomponent is obtained by using individual diode currentsshown in (1) where 119868IREC
119899+1
is rectifier side DC component ofcurrent at 119899 + 1 sample and 119868
1198861199041 1198681198871199041 and 119868
1198881199041are (119899 + 1)th
sample of source side currents of Phase (119886) (119887) and (119888)respectively in Inverter
The equation for inverter side DC link current compo-nent is obtained by using individual switch currents anddiode currents shown in (2) where 119868INV
119899+1
is inverter sideDC Component of DC link current at (119899 + 1)th sample1198681198791198801
1198681198791198802
and 1198681198791198803
are 119899th sample of upper switch cur-rents and 119868
1198791198711 1198681198791198712
and 1198681198791198713
are (119899 + 1)th sample of lowerswitch currents of phases (119886) (119887) and (119888) respectively inInverter
119868DC119899+1
= 119868REC119899+1
minus 119868INV119899+1
(3)
0 002 004 006 008 01
0
50
100
150
Time (s)
Curr
ent (
A)
minus50
minus100
II A Phase source REF
Diode rectifier source current Ts = 1120583s decoupled Ts = 100120583s
I A Phase source RTDS
Figure 4 Diode rectifier side source current in phase A for bothREF (blue trace) and RTDS (red traces)
0 002 004 006 008 010
50
100
150
200
250
300
350
400
450Vo
ltage
s (V
)
Time (s)
DC link voltage and its PLECS Ref Ts = 1120583s RTS Ts = 100120583s
Vdc link-RTDSVdc link-Ref
Figure 5 DC link voltage REF (blue trace) RTDS (red trace)
where 119868DC119899+1
is capacitor current at 119899 + 1 sampleFrom (3) DC link voltage of (119899 + 1)th sample can be
calculated as
119881DC119899+1
= 119881DC119899
+ (ℎ
119862dc) lowast 119868DC
119899+1
(4)
This sample is used to formulate the four different casesand its switching logic for an inverter circuit explainedin Section 3 for identifying all these parameters for nextiteration or time step
3 Modelling of IGBT-Diode Inverter andInduction Machine
Consider the IGBT-diode inverter circuit as in Figure 3 withinduction machine load Assume that two DC link voltages
4 Advances in Power Electronics
are equal (119881dc2 each) Then voltage at the DC link midpointis at zero potential Similarly Ea Eb and Ec are considered tobe back emf of induction machine in each phase and ldquo119873rdquo isthe neutral point of the induction machine stator windingsLet us assume that 119881
1198860 1198811198870 and 119881
1198880are the pole voltages of
each phase legConsider only that phases leg A and P
119880 P119871are the PWM
pulses to upper (T1198801) and lower (T
1198711) IGBT switches If
we define modes of operation for the phase leg A aloneby considering its state variables and PWM sequenceswe arrive at four different examples as given in whatfollows
Case 1 (119875119880
= 1 119875119871
= 0) upper IGBT switches on condition
(((05 sdot 119881dc minus 119864119909) gt 0) ampamp ((119875
119906minus 119875119897) == 1)
100381710038171003817100381710038171003817((119868 lt 0)ampamp((119877119868 + 119871 (
119868 minus 119868119863119906
119867) + 119864119909
+ 119881119873119874
) gt 05119881dc))
119868119879119880
=(1 + sign (119868))
2lowast 119875119880
119868 119868119863119880
=(1 minus sign (119868))
2lowast (1 minus 119875
119871) 119868
119881119909119900
= (119875119906
minus 119875119871) sdot
119881dc2
(5)
Case 2 (119875119880
= 0 119875119871
= 1) lower IGBT switches on condition
(((minus05 sdot 119881dc minus 119864119909) gt 0)ampamp ((119875
119906minus 119875119897) == minus1)
100381710038171003817100381710038171003817((119868 gt 0)ampamp((119877119868 + 119871 (
119868 minus 119868119863119906
119867) + 119864119909
+ 119881119873119874
) gt minus05119881dc))
119868119879119871
=(1 minus sign (119868))
2lowast 119875119871119868 119868
119879119880=
(1 + sign (119868))
2lowast (1 minus 119875
119880) 119868
119881119909119900
= (119875119906
minus 119875119871) sdot
119881dc2
(6)
Case 3 (119875119880
= 1 119875119871
= 1) shorted leg mode
119868119909119899+1
= 119868119909119899exp(minus
119905
119879) (7)
Case 4 (119875119880
= 0 119875119871
= 0) diode bridge mode IGBT switchesoff conditionCase 41 If
((119864119909
+ 119881119873119874
) gt 05119881dc)
119868119863119880
= 119868
119868119879119880
= 0
119881119909119900
=119881dc2
(8)
Case 42 If
((119864119909
+ 119881119873119874
) gt minus05119881dc)
119868119863119880
= 119868
119868119879119880
= 0
119881119909119900
= minus119881dc2
(9)
Case 43 If
(1003816100381610038161003816119864119909 + 119881
119873119874
1003816100381610038161003816 lt 05119881dc)ampamp119868 = 0
119868119863119880
= 0
119868119879119880
= 0
119881119909119900
= 0
(10)
where 119875119880is PWMpulse to upper switch 119875
119871is PWMpulse to
lower switch 119909 are phases (119886) (119887) and (119888) and 119868 is inductionmachine current in (119886) (119887) and (119888) reference frames
Advances in Power Electronics 5
001 002 003 004 005 006 007 008 009 01
0
100
200
300
DC link two-level (IGBT-diode) inverter
minus100
minus200
minus300
V PhA to neutral RTDSV PhA to neutral REF
Time (s)
Van
(V)
Figure 6 Inverter phase A neutral (Van) voltage REF (blue trace)RTDS (red traces)
002 004 006 008 01 012 014 016 018 02
0
10
20
30
40
50
60
Torq
ue (N
m)
DC link two-level (IGBT-diode) inverter
Torque RTDSTorque REF
Time (s)
Applied torque T load
Figure 7 Torque developed REF (blue trace) RTDS (red trace)
The logic for two IGBT switches in phase ldquo119886rdquo is given inwhat follows based on the conditions given previously as perfour different cases
1198791199061198861
= (((Sign (1198681199041198860
) = 1)1003817100381710038171003817 (1198681199041198860
= 0))ampamp
(((05 lowast 119881dc0 minus 11988111989911989900
) ge 0)ampamp
(1198751199061198861
minus 1198751198971198861
) = 1))
1198791198971198861
= (((Sign (1198681199041198860
) = minus1)1003817100381710038171003817 (1198681199041198860
= 0))ampamp
(((minus05 lowast 119881dc0 minus 11988111989911989900
) le 0)ampamp
(1198751199061198861
minus 1198751198971198861
) = minus1))
(11)
Similar logic for other two phases (119887) and (119888) is obtainedby replacing the subscript ldquo119886rdquo in earlier two equations by ldquo119887rdquoand ldquo119888rdquo Switching logic for the diode is explained in detail in[8] and hence has not been given here Similarly switchingfunction logic for IGBT-diode combination from individualIGBT logic and Diode logic is given later for all the switchesin upper legs and lower legs
Phase leg A top switches on (either IGBT or diode)
1198781199061198861
= 1198791199061198861
1003817100381710038171003817 1198631199061198861
1198781198971198861
= 1198791198971198861
1003817100381710038171003817 1198631198971198861
(12)
Phase leg B top switches on (either IGBT or diode)
1198781199061198871
= 1198791199061198871
1003817100381710038171003817 1198631199061198871
1198781198971198871
= 1198791198971198871
1003817100381710038171003817 1198631198971198871
(13)
Phase leg C top switches on (either IGBT or diode)
1198781199061198881
= 1198791199061198881
1003817100381710038171003817 1198631199061198881
1198781198971198881
= 1198791198971198881
1003817100381710038171003817 1198631198971198881
(14)
Phase to DC link midpoint voltage is given by
11988111988601
= 05 lowast 119881dc0 lowast (1198781199061198861
minus 1198781198971198861
)
11988111988701
= 05 lowast 119881dc0 lowast (1198781199061198871
minus 1198781198971198871
)
11988111988801
= 05 lowast 119881dc0 lowast (1198781199061198881
minus 1198781198971198881
)
(15)
Machine side of each phase voltage is given by
1198811198861198991
= (1
3) lowast (2 lowast 119881
11988601minus 11988111988701
minus 11988111988801
)
1198811198871198991
= (1
3) lowast (minus119881
11988601+ 2 lowast 119881
11988701minus 11988111988801
)
1198811198881198991
= (1
3) lowast (minus119881
11988601minus 11988111988701
+ 2 lowast 11988111988801
)
(16)
Voltages 1198811198861198991
1198811198871198991
and 1198811198881198991
in the previously equationare used as an input stator voltage for induction motor Inorder to find the various electrical and mechanical parame-ters like speed flux and current through stator terminals asimplified or reduced order model has to be developed whichhas been explained in detail later
While modelling induction machine the order of thesystem plays an important role in real-time simulation [9]In general induction machine is modelled in two-phasereference frame Sometimes this leads to more state matrixparameters and more computation time At the same timeif it is modelled as the lowest order system then the state
6 Advances in Power Electronics
variables may deviate from its actual values this leads to pooraccuracy and instability In order to compromise betweenaccuracy and computation time the induction machine ismodelled in stationary two-phase reference frame (120572-120573)
which satisfies the previous criteria This model has advan-tages like fewer matrix parameters calculation preservationof symmetry of the induction machine model state matrixand minimization of computation time [9 10]
Induction machine model in 120572-120573 reference frame is asfollows
119889
119889119905119883 (119905) = [119860
119888(120596)] 119883 (119905) + [119861
119888] 119880 (119905)
119884 (119905) = [119862119888] 119883 (119905)
(17)
where the input vector [U(t)] is chosen to be the reference120572-120573 stator voltages [X(t)] is the 120572-120573 stator and rotor fluxstate vector (input) [Y(t)] is the 120572-120573 stator and rotor currentoutput vector (output) and [119860
119888(120596)] [119861
119888] and [119862
119888] are state
matrix input matrix and output matrix respectivelyAs per the reference from [9 10] induction machine
equation in 120572-120573 is expressed in complete form as shown inwhat follows
119889
119889119905
[[[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]]]
]
=
[[[[[[[[[
[
minus119877119904
1205901198711199040
(1 minus 120590) 119877119904
120590119872119904119903
0
0minus119877119904
1205901198711199040
(1 minus 120590) 119877119904
120590119872119904119903
(1 minus 120590)
120590119872119904119903
119877119903 0minus119877119903
120590119871119903minus119901120596
0(1 minus 120590)
120590119872119904119903
119877119903 119901120596minus119877119903
120590119871119903
]]]]]]]]]
]
times
[[[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]]]
]
+
[[[[[
[
1 0
0 1
0 0
0 0
]]]]]
]
[V119904120572
V119904120573
]
[[[
[
119894119904120572
119894119904120573
119894119903120572
119894119903120573
]]]
]
=
[[[[[[[[[[[
[
1
1205901198711199040
minus (1 minus 120590)
120590119872119904119903
0
01
1205901198711199040
minus (1 minus 120590)
120590119872119904119903
minus (1 minus 120590)
120590119872119904119903
01
120590119871119903minus119901120596
0minus (1 minus 120590)
120590119872119904119903
1199011205961
120590119871119903
]]]]]]]]]]]
]
times[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]
]
002 004 006 008 01 012 014 016 018 02
0
20
40
60
80
100
120
140
DC link two-level (IGBT-diode) inverter
Speed radianss RTDSSpeed radianss REF
minus20
Time (s)
Wm
(rad
s)
Figure 8 Rotor speed in rads REF (blue trace) RTDS (red trace)
002 004 006 008 01 012 014 016 018 02
0
10
20
30
40
50
IL-p
hA (A
)DC link two-level (IGBT-diode) inverter
IL-phaseA RTDSIL-phaseA REF
Time (s)
minus10
minus20
minus30
minus40
Figure 9 Stator ph-A current REF (blue trace) RTDS (red trace)
[[[
[
119894119904120572
119894119904120573
120593119903120572
120593119903120573
]]]
]
119899+1
=[[[
[
11989211 11989212 11989213 11989214
11989221 11989222 11989223 11989224
11989231 11989232 11989233 11989234
11989241 11989242 11989243 11989244
]]]
]
times[[[
[
119894119904120572
119894119904120573
120593119903120572
120593119903120573
]]]
]
119899
+[[[
[
ℎ11 ℎ12
ℎ21 ℎ22
ℎ31 ℎ32
ℎ41 ℎ42
]]]
]
[119881119904120572
119881119904120573
]
119899
(18)
where 120590 = 1minus(1198722
119904119903119871119904119871119903) p = no of pole pairs in a machine
and 120596 = speed in rads
Advances in Power Electronics 7
002 004 006 008 01 012 014 016 018 02
0
50
100
150
EMF
phas
e A (V
)DC link two-level (IGBT-diode) inverter
EMF phase A RTDS
minus50
minus100
minus150
Time (s)
Figure 10 Stator ph-A back EMF-REF (blue trace) RTDS (redtrace)
Three-phaseinverter Load
PWM pulses MATLABCode
composerstudio
UncontrolledrectifierAC power
input
DSP1
DSP2
IGBT inverter module-1 IGBT inverter
module-2
RTDS
DSP1
DSP2
UART
DC linkvoltage AC power
output
Figure 11 Block diagram and snapshot of hardware setup
In order to find back emf set 119894119904120572
= 0 and 119894119904120573
= 0 Then119864119904120572
= 119881119904120572 119864119904120573
= 119881119904120573
[119864119904120572
119864119904120573
]
119899
=minus1
(ℎ11 sdot ℎ22 minus ℎ21 sdot ℎ12)[
ℎ22 minusℎ12
minusℎ21 ℎ11]
times [11989213 11989214
11989223 11989224] [
120593119903120572
120593119903120573
]
119899
(19)
ePWM3
WAWB
C280xC28x3xePWM
ePWM2
WAWB
C280xC28x3x
ePWM
ePWM1
WA
WB
C280xC28x3x
ePWM
Sine wave3
Sine wave2
Sine wave1
F28335 eZdsp
Data type conversion2
Uint16
Data type conversion1
Uint16
Data type conversion
Uint16
Figure 12 DSP interface for PWM pulse generation
Table 1 Input parameters for RTDS and Simulink-PLECS
Source parameters DC link inverter Load parametersVm = 1414 lowast 220119891 = 50120596 = 2 lowast pi lowast 119891Rs = 1Ω
Ls = 10mH
Cdc = 10mFFsw = 450Hz119867 = 100119890 minus 6 s
119898 = 08
As given in Table 3
where g119898119899 h119898119899
are the state and input matrix coefficients ofthe stationary reference frame model of induction machineAt every sampling time stator currents have been calculatedusing stator voltages and finally back emf of each phasehas been calculated as per (19) Current sample of back emfhas been used for the next iteration to identify the mode ofoperation of inverter given in Section 3With these equationsa generalized model of the complete electrical drive systemhas been developed and validated with offline Simulink-PLECS model given later
4 Simulation Results
Input parameters for proposedmodel as well as for Simulink-PLECS (REF) offline simulation are shown in Table 1
41 Offline Results versus Real-Time Digital Simulator Inthis case simulations are carried out with both rectifier andinverter now decoupled at DC link Both circuits are treatedas separate circuits and rectifier current with DC link andinverter current with DC link are calculated separately At theend of the iteration DC link voltage will be updated using therectifier and inverter currents
In Figures 4 5 6 7 8 9 and 10 red trace is fromSimulink-PLECS reference results which are overplotted onthat of RTDS-decoupled solution From Figures 4ndash10 it isvery clear that proposed real-timemodel and offline Simulinkresults are matching each other in terms of accuracy as wellas with larger step size of 100120583119904 proposedmodel with the 1120583119904
Simulink reference modelTable 2 shows that at a particular time of sample electrical
and mechanical parameters of real-time electrical drive
8 Advances in Power Electronics
10050
0minus50
minus100018 0185 019 0195 02 0205 021 0215 022 0225
Time (s)
Input phase-phase voltage
Phas
e-ph
ase
volta
ge (V
)
2010
0minus10minus20
Input current (R-phase)
Inpu
t R-p
hase
curr
ent (
A)
018 0185 019 0195 02 0205 021 0215 022 0225Time (s)
(a)
80604020
002 0202 0204 0206 0208 021 0212 0214 0216 0218 022
Time (s)
DC
link
(V)
DC link voltage
201510
50
minus5
DC
link
curr
ent (
A)
02 0202 0204 0206 0208 021 0212 0214 0216 0218 022Time (s)
DC link current
(b)
105
0019 0195 02 0205 021 0215 022 0225 023 0235
Time (s)
Gat
e pul
se (V
) Gate pulses for leg 1
Gate pulses for leg 2
Gate pulses for leg 3
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
Gat
e pul
se (V
)
105
0
105
0
Gat
e pul
se (V
)
(c)
10050
0minus50
minus10002 0205 021 0215 022 0225 023 0235 024 0245
Time (s)
AC output voltagePh
ase-
phas
evo
ltage
(V)
3210
minus1minus2minus3
R-ph
ase c
urre
nt (A
) AC output current (R-phase)
02 0205 021 0215 022 0225 023 0235 024 0245Time (s)
(d)
Figure 13 Proposed mathematical model offline results showing (a) input voltage (ph-ph) and current (R-phase) (b) DC link voltage andcurrent (c) PWM pulses for 3 legs of inverter and (d) output voltage (ph-ph) and current (R-Phase)
Table 2 Comparison of proposed real-time digital simulator results with Simulink-PLECS offline results
S no Parameter Time of sampleReferenceSimulink-PLECS(119886)
Proposed RTDSsolution
(119887)
Percentage of error ()((119887) minus (119886))(119886)
1 DC link voltage V 001 8546 8588 04910102 5001 5009 01
2 Rectifier source current in phase A Amps 0008 1215 1214 minus00820086 2418 2471 219
3 Stator current in phase A Amps 0009512 5195 518 minus000288008951 5596 555 minus000822
4 Inverter line to neutral voltage van (V) 0009512 3333 3333 0008951 3333 3333 0
5 Electromagnetic torque tem (N-m) 001186 6633 6686 0701985 2202 2202 00
6 Rotor speed 120596 (rads) 002 3141 3171 0901922 14848 14851 002
Advances in Power Electronics 9
(a) (b)
(c) (d)
Figure 14 Hardware results from DSP showing (a) input voltage (ph-ph) and current (R-Phase) (b) DC link voltage and current (c) PWMpulses for 3 legs of inverter from DSP and (d) output voltage (ph-ph) and current (R-phase)
systemmodel utilizingAC-DC-AC topology listed previouslyare closelymatchedwith its Simulink reference offline results
5 Real-Time Implementation Using DSP
The given system model is implemented in MATLAB m-file coding and also in real-time hardware setup using theDSP-MATLAB interface PWM are pulses for hardware andMATLAB model generated using DSP processor 2 ePWMmodule is used to generate six pulses at a time from ePWMpins of DSP These pulses are being fed to optocoupler TLP250 which boosts up the voltage level to an extent at whichIGBT switches can be triggered At the same time anotherprocessor is used to run the mathematical model of drivesystem as per decoupled method
Figure 11 represents the block diagram of the hard-ware setup As per specifications given in Appendix A twoSemikron make IGBT IPM module-based inverters used forthis purpose one acts as a rectifier and the other is used as aninverter to drive inductionmotor Pulses fromDSP2 are givento the Semikron inverter module 2 through the optoisolatorICs in order to strengthen the gate drive signal The PWMlogic is developed in Simulink model and Figure 12 showsthe logic generation of bipolar PWM for three-phase inverterComparative results are obtained for the input ph-ph voltageof diode rectifier and input phase current as shown in Figures13(a) and 14(a) Figures 13(b) and 14(b) show DC link voltageand current waveforms
The PWM pulses generated at the output of the optoiso-lator are shown in Figure 14(c) and those from the simulationare shown in Figure 13(c) In Figure 14 all voltage waveformsare phase-phase voltages with the multiplier setting of 200and all current waveforms are phase A current waveforms
with the probe setting at 10mVA Figures 13 and 14(d)reveal that the output voltage between two phases and phasecurrents is closely matched with that of the offline simulationresults As per analytical calculations as well as simulationand hardware results the output RMS voltage obtained acrossthe load is 85V All the parameters are matched except forthe grid voltage and current since it has been assumed as theideal source in simulation model and real grid conditions inthe laboratory are ignored But in practical situations the gridcould be connected to transformers and many other loads inthe laboratory building
6 Conclusion
A new research platform for power electronics and drivesystem modelling using decoupled analytical method hasbeen verified both in offline simulation and in real-timehardware The m-file program developed for state-spacemethod-based electrical drive model accurately matchingwith hardware model The same model has been validatedusing eZdsp processors with one as plant and the other asa controller Decoupled method makes it easier with betteraccuracy and less calculation time which results in fastexecution speed This can be further extended to test thesame with reduced order induction motor model and resultscan be compared with existing results in order to furtherimprovise the real-time model accuracy and its executiontime The results obtained from this work suggest that thedeveloped models using the proposed method can be usedas a research platform and extended to any complex powerelectronic applications The obtained model is flexible andit can be extended to any system with different size (systemorder) These models can be used as user definedfunction
10 Advances in Power Electronics
Table 3 Load specification three-phase induction motor
Parameter Value DescriptionkVAbase 4e3 Rated kVA of the machineVbase 400 Rated voltage (L-L) in (V)Vm 231 lowast radic2 Peak value of AC source voltage (V)119891 50 Rated frequency in Hz120596 2 lowast pi lowast 50 Rated angular frequency in radsRs 1405 Stator resistance in Ω
Ls(Lls + Lm) 0178039 Stator inductance in HRr 1395 Rotor resistance in Ω
Lr(Llr + Lm) 0178039 Rotor inductance in HLm 01722 Stator-rotor mutual inductance in Hℎ 100 Time step in 120583s119899 9 Carrier frequency 119899 times 50Hz119869 00131 Inertia of the machine in kgm2
119861 001841 Friction coefficient in Nmsrad119901 2 No of pole pairs
blocks to test with real-time processorcontroller for futureresearch work
Appendices
A Three-Phase IGBT-Based Inverter(Semikron Make)
IGBT module used SKM75GB123DDC link capacitor 4700 120583FGate driver SKYPER 32 PRO119881dc input 800 (V)119881ac output 415 (V)119868ac output 20 (A)Output frequency 50HzSwitching frequency 10 kHzType of cooling force air cooledTemp 35∘CDuty class class I
B
For more details see Table 3
References
[1] P Livinti and R Pusca ldquoControl of an electric drive system inthe LabVIEWprogramming environmentrdquo inProceedings of the9th International Conference on Remote Engineering and VirtualInstrumentation (REV) pp 1ndash6 Bilbao Spain July 2012
[2] R Champagne L A Dessaint andH Fortin-Blanchette ldquoReal-time simulation of electric drivesrdquoMathematics and Computersin Simulation vol 63 no 3-5 pp 173ndash181 2003
[3] H Eren and C C Fung ldquoVirtual instrumentation of electricdrive systems for automation and testingrdquo in Proceedings ofthe 17th IEEE Instrumentation and Measurement TechnologyConference (IMTC rsquo00) vol 3 pp 1500ndash1505 May 2000
[4] R Champagne L Dessaint G Sybille and B KhodabakhchianldquoApproach for real-time simulation of electric drivesrdquo in Pro-ceedings of the Canadian Conference on Electrical and ComputerEgineering (CCECE rsquo00) vol 1 pp 340ndash344 May 2000
[5] C Bordas C Dufour and O Rudloff ldquoA 3-level neutral-clamped inverter model with natural switching mode sup-port for the real-time simulation of variable speed drivesrdquoin Proceedings of the International Symposium on AdvancedElectromechanical Motion Systems pp 1ndash8 Lille France 2009
[6] A Myaing and V Dinavahi ldquoFPGA-based real-time emulationof power electronic systems with detailed representation ofdevice characteristicsrdquo IEEE Transactions on Industrial Elec-tronics vol 58 no 1 pp 358ndash368 2011
[7] J H Allmeling and W P Hammer ldquoPLECSmdashpiece-wise linearelectrical circuit simulation for Simulinkrdquo in Proceedings of theIEEE International Conference on Power Electronics and DriveSystems (PEDSrsquo99) vol 1 pp 355ndash360 July 1999
[8] S Venugopal and G Narayanan ldquoDesign of FPGA based digitalplatform for control of power electronics systemsrdquo in Proceed-ings of the National Power Electronics Conference pp 1250ndash1255December 2005
[9] K Jayalakshmi and V Ramanarayanan ldquoReal-time simulationof electrical machines on FPGA platformrdquo in Proceedings of theIndia International Conference on Power Electronics (IICPE rsquo06)pp 259ndash263 Chennai India December 2006
[10] R Krishnan Electric Motor Drives Modeling Analysis andControl Pearson Education Asia 2007
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
2 Advances in Power Electronics
sim
Inductionmotor
sim
sim
IREC IINV
IDC
Vdc
Vsa
VsbVsc
D1 T D2 T D3 T
D1 B D2 B D3 B
TU1 TU2 TU3
TL1 TL2 TL3
Du1 Du2 Du3
Dl1 Dl2 Dl3
Figure 1 Three-phase converter topology with diode rectifier DC link and inverter fed IM
simVdc
sim
sim
D1 T D2 T D3 T
D1 B D2 B D3 B
Vsa
Vsb
Vsc
(a)
+minus
+minus
Inductionmotor
Vdc2
0
Vdc2
TU1 TU2 TU3
TL1 TL2 TL3
Du1 Du2 Du3
Dl1 Dl2 Dl3
(b)
Figure 2 (a) Circuit 1 diode rectifier with DC link (b) Circuit 2 inverter fed induction motor with DC source
simple and allows developing the analytical equations suitablefor any power electronic system by decoupling rectifier andinverter This also gives exact solution and error is almostreduced
In this paper decoupled method for a simple three-phaseDC link inverter fed induction machine is proposed Thetopology of the converter considered in this paper comprisesdiode rectifier capacitive DC link PWM IGBT inverterand induction motor as load Decoupled analytical methodis used to solve all the state variables of the earlier testcircuit (source current DC link voltage and load current)for accurate results Decoupling is implemented to reducethe system equation order so as to achieve fast calculationand easier to get an analytical expression from solution tostate-space equations of the two converters Performanceparameters of the drive system have been validated usingMATLAB scripts (m-file) and also on DSP platform Thismethod has advantages like reduced system order simplifiedsolution easier calculation exact zero crossing and less datastorage due to large step size comparing coupled method
2 Methodology
Figure 1 represents the topology of the power converter tobe modelled with decoupled algorithm with zero crossingIn every sampling period of the discrete model two circuitsare considered The first part of the circuit consists of an AC
voltage source having an internal impedance connected to adiode rectifier with a DC link capacitor The second part ishaving a constant voltage source in DC link PWM inverterand an IM load At the end of every sampling period DC linkvoltage is computed by integrating the difference in rectifierand inverter currents
The proposed decoupled algorithm to solve the state-space equation of the electric drive system is given later
Step 1 Initialization parameters of the selected system
Step 2 Decouple the diode bridge rectifier and inverter fedinduction motor circuit
Step 3 Define different cases with an equivalent circuit fortwo decoupled circuits
Step 4 Assume that 119881dc0 is a known value (initial value = 0)
Step 5 Solve state-space equation of the diode bridgerectifier and find rectifier side DC link current (119868REC)
using analyticalnumerical method based on its switchingstatesfunction
Step 6 Solve state-space equation of inverter fed induc-tion motor and find inverter side DC links current (119868INV)
using analyticalnumerical method based on its switchingstatesfunction (see Figure 2)
Advances in Power Electronics 3
PU
Va
Vb
Vc
+minus
+minus
0Vdc2
Vdc2
N
sim
sim
sim
Ea
Eb
Ec
Lla
Llb
Llc
Rla
Rlb
Rlc
PL
TU1 TU2 TU3Du1 Du2 Du3
TL1 TL2 TL3Dl1 Dl2 Dl3
Figure 3 IGBT-diode inverter circuit with equivalent inductionmotor
Step 7 Find capacitor current 119868DC119899+1
using rectifier andinverter side DC link currents from Steps 5 and 6 respec-tively
Step 8 Solve the differential equation of DC link current andfind 119881DC
119899+1
using analyticalnumerical method
Step 9 Repeat the iteration for all cases up to stop time
Step 10 Compare with offline simulation results usingSimulinkSimulation tool
119868REC119899+1
= ((05 lowast (1 + sign (119868119886119904119899+1
) lowast 119868119886119904119899+1
)
+ (05 lowast (1 + sign (119868119887119904119899+1
)) lowast 119868119887119904119899+1
)
+ (05 lowast (1 + sign (119868119888119904119899+1
)) lowast 119868119888119904119899+1
)))
(1)
119868INV119899+1
= 05 lowast ((1198681198791198801
+ 1198681198631198801
) minus (1198681198791198711
+ 1198681198631198711
)
+ (1198681198791198802
+ 1198681198631198802
) minus (1198681198791198712
+ 1198681198631198712
)
+ (1198681198791198803
+ 1198681198631198803
) minus (1198681198791198713
+ 1198681198631198713
))
(2)
The equation for diode rectifier side DC link currentcomponent is obtained by using individual diode currentsshown in (1) where 119868IREC
119899+1
is rectifier side DC component ofcurrent at 119899 + 1 sample and 119868
1198861199041 1198681198871199041 and 119868
1198881199041are (119899 + 1)th
sample of source side currents of Phase (119886) (119887) and (119888)respectively in Inverter
The equation for inverter side DC link current compo-nent is obtained by using individual switch currents anddiode currents shown in (2) where 119868INV
119899+1
is inverter sideDC Component of DC link current at (119899 + 1)th sample1198681198791198801
1198681198791198802
and 1198681198791198803
are 119899th sample of upper switch cur-rents and 119868
1198791198711 1198681198791198712
and 1198681198791198713
are (119899 + 1)th sample of lowerswitch currents of phases (119886) (119887) and (119888) respectively inInverter
119868DC119899+1
= 119868REC119899+1
minus 119868INV119899+1
(3)
0 002 004 006 008 01
0
50
100
150
Time (s)
Curr
ent (
A)
minus50
minus100
II A Phase source REF
Diode rectifier source current Ts = 1120583s decoupled Ts = 100120583s
I A Phase source RTDS
Figure 4 Diode rectifier side source current in phase A for bothREF (blue trace) and RTDS (red traces)
0 002 004 006 008 010
50
100
150
200
250
300
350
400
450Vo
ltage
s (V
)
Time (s)
DC link voltage and its PLECS Ref Ts = 1120583s RTS Ts = 100120583s
Vdc link-RTDSVdc link-Ref
Figure 5 DC link voltage REF (blue trace) RTDS (red trace)
where 119868DC119899+1
is capacitor current at 119899 + 1 sampleFrom (3) DC link voltage of (119899 + 1)th sample can be
calculated as
119881DC119899+1
= 119881DC119899
+ (ℎ
119862dc) lowast 119868DC
119899+1
(4)
This sample is used to formulate the four different casesand its switching logic for an inverter circuit explainedin Section 3 for identifying all these parameters for nextiteration or time step
3 Modelling of IGBT-Diode Inverter andInduction Machine
Consider the IGBT-diode inverter circuit as in Figure 3 withinduction machine load Assume that two DC link voltages
4 Advances in Power Electronics
are equal (119881dc2 each) Then voltage at the DC link midpointis at zero potential Similarly Ea Eb and Ec are considered tobe back emf of induction machine in each phase and ldquo119873rdquo isthe neutral point of the induction machine stator windingsLet us assume that 119881
1198860 1198811198870 and 119881
1198880are the pole voltages of
each phase legConsider only that phases leg A and P
119880 P119871are the PWM
pulses to upper (T1198801) and lower (T
1198711) IGBT switches If
we define modes of operation for the phase leg A aloneby considering its state variables and PWM sequenceswe arrive at four different examples as given in whatfollows
Case 1 (119875119880
= 1 119875119871
= 0) upper IGBT switches on condition
(((05 sdot 119881dc minus 119864119909) gt 0) ampamp ((119875
119906minus 119875119897) == 1)
100381710038171003817100381710038171003817((119868 lt 0)ampamp((119877119868 + 119871 (
119868 minus 119868119863119906
119867) + 119864119909
+ 119881119873119874
) gt 05119881dc))
119868119879119880
=(1 + sign (119868))
2lowast 119875119880
119868 119868119863119880
=(1 minus sign (119868))
2lowast (1 minus 119875
119871) 119868
119881119909119900
= (119875119906
minus 119875119871) sdot
119881dc2
(5)
Case 2 (119875119880
= 0 119875119871
= 1) lower IGBT switches on condition
(((minus05 sdot 119881dc minus 119864119909) gt 0)ampamp ((119875
119906minus 119875119897) == minus1)
100381710038171003817100381710038171003817((119868 gt 0)ampamp((119877119868 + 119871 (
119868 minus 119868119863119906
119867) + 119864119909
+ 119881119873119874
) gt minus05119881dc))
119868119879119871
=(1 minus sign (119868))
2lowast 119875119871119868 119868
119879119880=
(1 + sign (119868))
2lowast (1 minus 119875
119880) 119868
119881119909119900
= (119875119906
minus 119875119871) sdot
119881dc2
(6)
Case 3 (119875119880
= 1 119875119871
= 1) shorted leg mode
119868119909119899+1
= 119868119909119899exp(minus
119905
119879) (7)
Case 4 (119875119880
= 0 119875119871
= 0) diode bridge mode IGBT switchesoff conditionCase 41 If
((119864119909
+ 119881119873119874
) gt 05119881dc)
119868119863119880
= 119868
119868119879119880
= 0
119881119909119900
=119881dc2
(8)
Case 42 If
((119864119909
+ 119881119873119874
) gt minus05119881dc)
119868119863119880
= 119868
119868119879119880
= 0
119881119909119900
= minus119881dc2
(9)
Case 43 If
(1003816100381610038161003816119864119909 + 119881
119873119874
1003816100381610038161003816 lt 05119881dc)ampamp119868 = 0
119868119863119880
= 0
119868119879119880
= 0
119881119909119900
= 0
(10)
where 119875119880is PWMpulse to upper switch 119875
119871is PWMpulse to
lower switch 119909 are phases (119886) (119887) and (119888) and 119868 is inductionmachine current in (119886) (119887) and (119888) reference frames
Advances in Power Electronics 5
001 002 003 004 005 006 007 008 009 01
0
100
200
300
DC link two-level (IGBT-diode) inverter
minus100
minus200
minus300
V PhA to neutral RTDSV PhA to neutral REF
Time (s)
Van
(V)
Figure 6 Inverter phase A neutral (Van) voltage REF (blue trace)RTDS (red traces)
002 004 006 008 01 012 014 016 018 02
0
10
20
30
40
50
60
Torq
ue (N
m)
DC link two-level (IGBT-diode) inverter
Torque RTDSTorque REF
Time (s)
Applied torque T load
Figure 7 Torque developed REF (blue trace) RTDS (red trace)
The logic for two IGBT switches in phase ldquo119886rdquo is given inwhat follows based on the conditions given previously as perfour different cases
1198791199061198861
= (((Sign (1198681199041198860
) = 1)1003817100381710038171003817 (1198681199041198860
= 0))ampamp
(((05 lowast 119881dc0 minus 11988111989911989900
) ge 0)ampamp
(1198751199061198861
minus 1198751198971198861
) = 1))
1198791198971198861
= (((Sign (1198681199041198860
) = minus1)1003817100381710038171003817 (1198681199041198860
= 0))ampamp
(((minus05 lowast 119881dc0 minus 11988111989911989900
) le 0)ampamp
(1198751199061198861
minus 1198751198971198861
) = minus1))
(11)
Similar logic for other two phases (119887) and (119888) is obtainedby replacing the subscript ldquo119886rdquo in earlier two equations by ldquo119887rdquoand ldquo119888rdquo Switching logic for the diode is explained in detail in[8] and hence has not been given here Similarly switchingfunction logic for IGBT-diode combination from individualIGBT logic and Diode logic is given later for all the switchesin upper legs and lower legs
Phase leg A top switches on (either IGBT or diode)
1198781199061198861
= 1198791199061198861
1003817100381710038171003817 1198631199061198861
1198781198971198861
= 1198791198971198861
1003817100381710038171003817 1198631198971198861
(12)
Phase leg B top switches on (either IGBT or diode)
1198781199061198871
= 1198791199061198871
1003817100381710038171003817 1198631199061198871
1198781198971198871
= 1198791198971198871
1003817100381710038171003817 1198631198971198871
(13)
Phase leg C top switches on (either IGBT or diode)
1198781199061198881
= 1198791199061198881
1003817100381710038171003817 1198631199061198881
1198781198971198881
= 1198791198971198881
1003817100381710038171003817 1198631198971198881
(14)
Phase to DC link midpoint voltage is given by
11988111988601
= 05 lowast 119881dc0 lowast (1198781199061198861
minus 1198781198971198861
)
11988111988701
= 05 lowast 119881dc0 lowast (1198781199061198871
minus 1198781198971198871
)
11988111988801
= 05 lowast 119881dc0 lowast (1198781199061198881
minus 1198781198971198881
)
(15)
Machine side of each phase voltage is given by
1198811198861198991
= (1
3) lowast (2 lowast 119881
11988601minus 11988111988701
minus 11988111988801
)
1198811198871198991
= (1
3) lowast (minus119881
11988601+ 2 lowast 119881
11988701minus 11988111988801
)
1198811198881198991
= (1
3) lowast (minus119881
11988601minus 11988111988701
+ 2 lowast 11988111988801
)
(16)
Voltages 1198811198861198991
1198811198871198991
and 1198811198881198991
in the previously equationare used as an input stator voltage for induction motor Inorder to find the various electrical and mechanical parame-ters like speed flux and current through stator terminals asimplified or reduced order model has to be developed whichhas been explained in detail later
While modelling induction machine the order of thesystem plays an important role in real-time simulation [9]In general induction machine is modelled in two-phasereference frame Sometimes this leads to more state matrixparameters and more computation time At the same timeif it is modelled as the lowest order system then the state
6 Advances in Power Electronics
variables may deviate from its actual values this leads to pooraccuracy and instability In order to compromise betweenaccuracy and computation time the induction machine ismodelled in stationary two-phase reference frame (120572-120573)
which satisfies the previous criteria This model has advan-tages like fewer matrix parameters calculation preservationof symmetry of the induction machine model state matrixand minimization of computation time [9 10]
Induction machine model in 120572-120573 reference frame is asfollows
119889
119889119905119883 (119905) = [119860
119888(120596)] 119883 (119905) + [119861
119888] 119880 (119905)
119884 (119905) = [119862119888] 119883 (119905)
(17)
where the input vector [U(t)] is chosen to be the reference120572-120573 stator voltages [X(t)] is the 120572-120573 stator and rotor fluxstate vector (input) [Y(t)] is the 120572-120573 stator and rotor currentoutput vector (output) and [119860
119888(120596)] [119861
119888] and [119862
119888] are state
matrix input matrix and output matrix respectivelyAs per the reference from [9 10] induction machine
equation in 120572-120573 is expressed in complete form as shown inwhat follows
119889
119889119905
[[[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]]]
]
=
[[[[[[[[[
[
minus119877119904
1205901198711199040
(1 minus 120590) 119877119904
120590119872119904119903
0
0minus119877119904
1205901198711199040
(1 minus 120590) 119877119904
120590119872119904119903
(1 minus 120590)
120590119872119904119903
119877119903 0minus119877119903
120590119871119903minus119901120596
0(1 minus 120590)
120590119872119904119903
119877119903 119901120596minus119877119903
120590119871119903
]]]]]]]]]
]
times
[[[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]]]
]
+
[[[[[
[
1 0
0 1
0 0
0 0
]]]]]
]
[V119904120572
V119904120573
]
[[[
[
119894119904120572
119894119904120573
119894119903120572
119894119903120573
]]]
]
=
[[[[[[[[[[[
[
1
1205901198711199040
minus (1 minus 120590)
120590119872119904119903
0
01
1205901198711199040
minus (1 minus 120590)
120590119872119904119903
minus (1 minus 120590)
120590119872119904119903
01
120590119871119903minus119901120596
0minus (1 minus 120590)
120590119872119904119903
1199011205961
120590119871119903
]]]]]]]]]]]
]
times[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]
]
002 004 006 008 01 012 014 016 018 02
0
20
40
60
80
100
120
140
DC link two-level (IGBT-diode) inverter
Speed radianss RTDSSpeed radianss REF
minus20
Time (s)
Wm
(rad
s)
Figure 8 Rotor speed in rads REF (blue trace) RTDS (red trace)
002 004 006 008 01 012 014 016 018 02
0
10
20
30
40
50
IL-p
hA (A
)DC link two-level (IGBT-diode) inverter
IL-phaseA RTDSIL-phaseA REF
Time (s)
minus10
minus20
minus30
minus40
Figure 9 Stator ph-A current REF (blue trace) RTDS (red trace)
[[[
[
119894119904120572
119894119904120573
120593119903120572
120593119903120573
]]]
]
119899+1
=[[[
[
11989211 11989212 11989213 11989214
11989221 11989222 11989223 11989224
11989231 11989232 11989233 11989234
11989241 11989242 11989243 11989244
]]]
]
times[[[
[
119894119904120572
119894119904120573
120593119903120572
120593119903120573
]]]
]
119899
+[[[
[
ℎ11 ℎ12
ℎ21 ℎ22
ℎ31 ℎ32
ℎ41 ℎ42
]]]
]
[119881119904120572
119881119904120573
]
119899
(18)
where 120590 = 1minus(1198722
119904119903119871119904119871119903) p = no of pole pairs in a machine
and 120596 = speed in rads
Advances in Power Electronics 7
002 004 006 008 01 012 014 016 018 02
0
50
100
150
EMF
phas
e A (V
)DC link two-level (IGBT-diode) inverter
EMF phase A RTDS
minus50
minus100
minus150
Time (s)
Figure 10 Stator ph-A back EMF-REF (blue trace) RTDS (redtrace)
Three-phaseinverter Load
PWM pulses MATLABCode
composerstudio
UncontrolledrectifierAC power
input
DSP1
DSP2
IGBT inverter module-1 IGBT inverter
module-2
RTDS
DSP1
DSP2
UART
DC linkvoltage AC power
output
Figure 11 Block diagram and snapshot of hardware setup
In order to find back emf set 119894119904120572
= 0 and 119894119904120573
= 0 Then119864119904120572
= 119881119904120572 119864119904120573
= 119881119904120573
[119864119904120572
119864119904120573
]
119899
=minus1
(ℎ11 sdot ℎ22 minus ℎ21 sdot ℎ12)[
ℎ22 minusℎ12
minusℎ21 ℎ11]
times [11989213 11989214
11989223 11989224] [
120593119903120572
120593119903120573
]
119899
(19)
ePWM3
WAWB
C280xC28x3xePWM
ePWM2
WAWB
C280xC28x3x
ePWM
ePWM1
WA
WB
C280xC28x3x
ePWM
Sine wave3
Sine wave2
Sine wave1
F28335 eZdsp
Data type conversion2
Uint16
Data type conversion1
Uint16
Data type conversion
Uint16
Figure 12 DSP interface for PWM pulse generation
Table 1 Input parameters for RTDS and Simulink-PLECS
Source parameters DC link inverter Load parametersVm = 1414 lowast 220119891 = 50120596 = 2 lowast pi lowast 119891Rs = 1Ω
Ls = 10mH
Cdc = 10mFFsw = 450Hz119867 = 100119890 minus 6 s
119898 = 08
As given in Table 3
where g119898119899 h119898119899
are the state and input matrix coefficients ofthe stationary reference frame model of induction machineAt every sampling time stator currents have been calculatedusing stator voltages and finally back emf of each phasehas been calculated as per (19) Current sample of back emfhas been used for the next iteration to identify the mode ofoperation of inverter given in Section 3With these equationsa generalized model of the complete electrical drive systemhas been developed and validated with offline Simulink-PLECS model given later
4 Simulation Results
Input parameters for proposedmodel as well as for Simulink-PLECS (REF) offline simulation are shown in Table 1
41 Offline Results versus Real-Time Digital Simulator Inthis case simulations are carried out with both rectifier andinverter now decoupled at DC link Both circuits are treatedas separate circuits and rectifier current with DC link andinverter current with DC link are calculated separately At theend of the iteration DC link voltage will be updated using therectifier and inverter currents
In Figures 4 5 6 7 8 9 and 10 red trace is fromSimulink-PLECS reference results which are overplotted onthat of RTDS-decoupled solution From Figures 4ndash10 it isvery clear that proposed real-timemodel and offline Simulinkresults are matching each other in terms of accuracy as wellas with larger step size of 100120583119904 proposedmodel with the 1120583119904
Simulink reference modelTable 2 shows that at a particular time of sample electrical
and mechanical parameters of real-time electrical drive
8 Advances in Power Electronics
10050
0minus50
minus100018 0185 019 0195 02 0205 021 0215 022 0225
Time (s)
Input phase-phase voltage
Phas
e-ph
ase
volta
ge (V
)
2010
0minus10minus20
Input current (R-phase)
Inpu
t R-p
hase
curr
ent (
A)
018 0185 019 0195 02 0205 021 0215 022 0225Time (s)
(a)
80604020
002 0202 0204 0206 0208 021 0212 0214 0216 0218 022
Time (s)
DC
link
(V)
DC link voltage
201510
50
minus5
DC
link
curr
ent (
A)
02 0202 0204 0206 0208 021 0212 0214 0216 0218 022Time (s)
DC link current
(b)
105
0019 0195 02 0205 021 0215 022 0225 023 0235
Time (s)
Gat
e pul
se (V
) Gate pulses for leg 1
Gate pulses for leg 2
Gate pulses for leg 3
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
Gat
e pul
se (V
)
105
0
105
0
Gat
e pul
se (V
)
(c)
10050
0minus50
minus10002 0205 021 0215 022 0225 023 0235 024 0245
Time (s)
AC output voltagePh
ase-
phas
evo
ltage
(V)
3210
minus1minus2minus3
R-ph
ase c
urre
nt (A
) AC output current (R-phase)
02 0205 021 0215 022 0225 023 0235 024 0245Time (s)
(d)
Figure 13 Proposed mathematical model offline results showing (a) input voltage (ph-ph) and current (R-phase) (b) DC link voltage andcurrent (c) PWM pulses for 3 legs of inverter and (d) output voltage (ph-ph) and current (R-Phase)
Table 2 Comparison of proposed real-time digital simulator results with Simulink-PLECS offline results
S no Parameter Time of sampleReferenceSimulink-PLECS(119886)
Proposed RTDSsolution
(119887)
Percentage of error ()((119887) minus (119886))(119886)
1 DC link voltage V 001 8546 8588 04910102 5001 5009 01
2 Rectifier source current in phase A Amps 0008 1215 1214 minus00820086 2418 2471 219
3 Stator current in phase A Amps 0009512 5195 518 minus000288008951 5596 555 minus000822
4 Inverter line to neutral voltage van (V) 0009512 3333 3333 0008951 3333 3333 0
5 Electromagnetic torque tem (N-m) 001186 6633 6686 0701985 2202 2202 00
6 Rotor speed 120596 (rads) 002 3141 3171 0901922 14848 14851 002
Advances in Power Electronics 9
(a) (b)
(c) (d)
Figure 14 Hardware results from DSP showing (a) input voltage (ph-ph) and current (R-Phase) (b) DC link voltage and current (c) PWMpulses for 3 legs of inverter from DSP and (d) output voltage (ph-ph) and current (R-phase)
systemmodel utilizingAC-DC-AC topology listed previouslyare closelymatchedwith its Simulink reference offline results
5 Real-Time Implementation Using DSP
The given system model is implemented in MATLAB m-file coding and also in real-time hardware setup using theDSP-MATLAB interface PWM are pulses for hardware andMATLAB model generated using DSP processor 2 ePWMmodule is used to generate six pulses at a time from ePWMpins of DSP These pulses are being fed to optocoupler TLP250 which boosts up the voltage level to an extent at whichIGBT switches can be triggered At the same time anotherprocessor is used to run the mathematical model of drivesystem as per decoupled method
Figure 11 represents the block diagram of the hard-ware setup As per specifications given in Appendix A twoSemikron make IGBT IPM module-based inverters used forthis purpose one acts as a rectifier and the other is used as aninverter to drive inductionmotor Pulses fromDSP2 are givento the Semikron inverter module 2 through the optoisolatorICs in order to strengthen the gate drive signal The PWMlogic is developed in Simulink model and Figure 12 showsthe logic generation of bipolar PWM for three-phase inverterComparative results are obtained for the input ph-ph voltageof diode rectifier and input phase current as shown in Figures13(a) and 14(a) Figures 13(b) and 14(b) show DC link voltageand current waveforms
The PWM pulses generated at the output of the optoiso-lator are shown in Figure 14(c) and those from the simulationare shown in Figure 13(c) In Figure 14 all voltage waveformsare phase-phase voltages with the multiplier setting of 200and all current waveforms are phase A current waveforms
with the probe setting at 10mVA Figures 13 and 14(d)reveal that the output voltage between two phases and phasecurrents is closely matched with that of the offline simulationresults As per analytical calculations as well as simulationand hardware results the output RMS voltage obtained acrossthe load is 85V All the parameters are matched except forthe grid voltage and current since it has been assumed as theideal source in simulation model and real grid conditions inthe laboratory are ignored But in practical situations the gridcould be connected to transformers and many other loads inthe laboratory building
6 Conclusion
A new research platform for power electronics and drivesystem modelling using decoupled analytical method hasbeen verified both in offline simulation and in real-timehardware The m-file program developed for state-spacemethod-based electrical drive model accurately matchingwith hardware model The same model has been validatedusing eZdsp processors with one as plant and the other asa controller Decoupled method makes it easier with betteraccuracy and less calculation time which results in fastexecution speed This can be further extended to test thesame with reduced order induction motor model and resultscan be compared with existing results in order to furtherimprovise the real-time model accuracy and its executiontime The results obtained from this work suggest that thedeveloped models using the proposed method can be usedas a research platform and extended to any complex powerelectronic applications The obtained model is flexible andit can be extended to any system with different size (systemorder) These models can be used as user definedfunction
10 Advances in Power Electronics
Table 3 Load specification three-phase induction motor
Parameter Value DescriptionkVAbase 4e3 Rated kVA of the machineVbase 400 Rated voltage (L-L) in (V)Vm 231 lowast radic2 Peak value of AC source voltage (V)119891 50 Rated frequency in Hz120596 2 lowast pi lowast 50 Rated angular frequency in radsRs 1405 Stator resistance in Ω
Ls(Lls + Lm) 0178039 Stator inductance in HRr 1395 Rotor resistance in Ω
Lr(Llr + Lm) 0178039 Rotor inductance in HLm 01722 Stator-rotor mutual inductance in Hℎ 100 Time step in 120583s119899 9 Carrier frequency 119899 times 50Hz119869 00131 Inertia of the machine in kgm2
119861 001841 Friction coefficient in Nmsrad119901 2 No of pole pairs
blocks to test with real-time processorcontroller for futureresearch work
Appendices
A Three-Phase IGBT-Based Inverter(Semikron Make)
IGBT module used SKM75GB123DDC link capacitor 4700 120583FGate driver SKYPER 32 PRO119881dc input 800 (V)119881ac output 415 (V)119868ac output 20 (A)Output frequency 50HzSwitching frequency 10 kHzType of cooling force air cooledTemp 35∘CDuty class class I
B
For more details see Table 3
References
[1] P Livinti and R Pusca ldquoControl of an electric drive system inthe LabVIEWprogramming environmentrdquo inProceedings of the9th International Conference on Remote Engineering and VirtualInstrumentation (REV) pp 1ndash6 Bilbao Spain July 2012
[2] R Champagne L A Dessaint andH Fortin-Blanchette ldquoReal-time simulation of electric drivesrdquoMathematics and Computersin Simulation vol 63 no 3-5 pp 173ndash181 2003
[3] H Eren and C C Fung ldquoVirtual instrumentation of electricdrive systems for automation and testingrdquo in Proceedings ofthe 17th IEEE Instrumentation and Measurement TechnologyConference (IMTC rsquo00) vol 3 pp 1500ndash1505 May 2000
[4] R Champagne L Dessaint G Sybille and B KhodabakhchianldquoApproach for real-time simulation of electric drivesrdquo in Pro-ceedings of the Canadian Conference on Electrical and ComputerEgineering (CCECE rsquo00) vol 1 pp 340ndash344 May 2000
[5] C Bordas C Dufour and O Rudloff ldquoA 3-level neutral-clamped inverter model with natural switching mode sup-port for the real-time simulation of variable speed drivesrdquoin Proceedings of the International Symposium on AdvancedElectromechanical Motion Systems pp 1ndash8 Lille France 2009
[6] A Myaing and V Dinavahi ldquoFPGA-based real-time emulationof power electronic systems with detailed representation ofdevice characteristicsrdquo IEEE Transactions on Industrial Elec-tronics vol 58 no 1 pp 358ndash368 2011
[7] J H Allmeling and W P Hammer ldquoPLECSmdashpiece-wise linearelectrical circuit simulation for Simulinkrdquo in Proceedings of theIEEE International Conference on Power Electronics and DriveSystems (PEDSrsquo99) vol 1 pp 355ndash360 July 1999
[8] S Venugopal and G Narayanan ldquoDesign of FPGA based digitalplatform for control of power electronics systemsrdquo in Proceed-ings of the National Power Electronics Conference pp 1250ndash1255December 2005
[9] K Jayalakshmi and V Ramanarayanan ldquoReal-time simulationof electrical machines on FPGA platformrdquo in Proceedings of theIndia International Conference on Power Electronics (IICPE rsquo06)pp 259ndash263 Chennai India December 2006
[10] R Krishnan Electric Motor Drives Modeling Analysis andControl Pearson Education Asia 2007
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
Advances in Power Electronics 3
PU
Va
Vb
Vc
+minus
+minus
0Vdc2
Vdc2
N
sim
sim
sim
Ea
Eb
Ec
Lla
Llb
Llc
Rla
Rlb
Rlc
PL
TU1 TU2 TU3Du1 Du2 Du3
TL1 TL2 TL3Dl1 Dl2 Dl3
Figure 3 IGBT-diode inverter circuit with equivalent inductionmotor
Step 7 Find capacitor current 119868DC119899+1
using rectifier andinverter side DC link currents from Steps 5 and 6 respec-tively
Step 8 Solve the differential equation of DC link current andfind 119881DC
119899+1
using analyticalnumerical method
Step 9 Repeat the iteration for all cases up to stop time
Step 10 Compare with offline simulation results usingSimulinkSimulation tool
119868REC119899+1
= ((05 lowast (1 + sign (119868119886119904119899+1
) lowast 119868119886119904119899+1
)
+ (05 lowast (1 + sign (119868119887119904119899+1
)) lowast 119868119887119904119899+1
)
+ (05 lowast (1 + sign (119868119888119904119899+1
)) lowast 119868119888119904119899+1
)))
(1)
119868INV119899+1
= 05 lowast ((1198681198791198801
+ 1198681198631198801
) minus (1198681198791198711
+ 1198681198631198711
)
+ (1198681198791198802
+ 1198681198631198802
) minus (1198681198791198712
+ 1198681198631198712
)
+ (1198681198791198803
+ 1198681198631198803
) minus (1198681198791198713
+ 1198681198631198713
))
(2)
The equation for diode rectifier side DC link currentcomponent is obtained by using individual diode currentsshown in (1) where 119868IREC
119899+1
is rectifier side DC component ofcurrent at 119899 + 1 sample and 119868
1198861199041 1198681198871199041 and 119868
1198881199041are (119899 + 1)th
sample of source side currents of Phase (119886) (119887) and (119888)respectively in Inverter
The equation for inverter side DC link current compo-nent is obtained by using individual switch currents anddiode currents shown in (2) where 119868INV
119899+1
is inverter sideDC Component of DC link current at (119899 + 1)th sample1198681198791198801
1198681198791198802
and 1198681198791198803
are 119899th sample of upper switch cur-rents and 119868
1198791198711 1198681198791198712
and 1198681198791198713
are (119899 + 1)th sample of lowerswitch currents of phases (119886) (119887) and (119888) respectively inInverter
119868DC119899+1
= 119868REC119899+1
minus 119868INV119899+1
(3)
0 002 004 006 008 01
0
50
100
150
Time (s)
Curr
ent (
A)
minus50
minus100
II A Phase source REF
Diode rectifier source current Ts = 1120583s decoupled Ts = 100120583s
I A Phase source RTDS
Figure 4 Diode rectifier side source current in phase A for bothREF (blue trace) and RTDS (red traces)
0 002 004 006 008 010
50
100
150
200
250
300
350
400
450Vo
ltage
s (V
)
Time (s)
DC link voltage and its PLECS Ref Ts = 1120583s RTS Ts = 100120583s
Vdc link-RTDSVdc link-Ref
Figure 5 DC link voltage REF (blue trace) RTDS (red trace)
where 119868DC119899+1
is capacitor current at 119899 + 1 sampleFrom (3) DC link voltage of (119899 + 1)th sample can be
calculated as
119881DC119899+1
= 119881DC119899
+ (ℎ
119862dc) lowast 119868DC
119899+1
(4)
This sample is used to formulate the four different casesand its switching logic for an inverter circuit explainedin Section 3 for identifying all these parameters for nextiteration or time step
3 Modelling of IGBT-Diode Inverter andInduction Machine
Consider the IGBT-diode inverter circuit as in Figure 3 withinduction machine load Assume that two DC link voltages
4 Advances in Power Electronics
are equal (119881dc2 each) Then voltage at the DC link midpointis at zero potential Similarly Ea Eb and Ec are considered tobe back emf of induction machine in each phase and ldquo119873rdquo isthe neutral point of the induction machine stator windingsLet us assume that 119881
1198860 1198811198870 and 119881
1198880are the pole voltages of
each phase legConsider only that phases leg A and P
119880 P119871are the PWM
pulses to upper (T1198801) and lower (T
1198711) IGBT switches If
we define modes of operation for the phase leg A aloneby considering its state variables and PWM sequenceswe arrive at four different examples as given in whatfollows
Case 1 (119875119880
= 1 119875119871
= 0) upper IGBT switches on condition
(((05 sdot 119881dc minus 119864119909) gt 0) ampamp ((119875
119906minus 119875119897) == 1)
100381710038171003817100381710038171003817((119868 lt 0)ampamp((119877119868 + 119871 (
119868 minus 119868119863119906
119867) + 119864119909
+ 119881119873119874
) gt 05119881dc))
119868119879119880
=(1 + sign (119868))
2lowast 119875119880
119868 119868119863119880
=(1 minus sign (119868))
2lowast (1 minus 119875
119871) 119868
119881119909119900
= (119875119906
minus 119875119871) sdot
119881dc2
(5)
Case 2 (119875119880
= 0 119875119871
= 1) lower IGBT switches on condition
(((minus05 sdot 119881dc minus 119864119909) gt 0)ampamp ((119875
119906minus 119875119897) == minus1)
100381710038171003817100381710038171003817((119868 gt 0)ampamp((119877119868 + 119871 (
119868 minus 119868119863119906
119867) + 119864119909
+ 119881119873119874
) gt minus05119881dc))
119868119879119871
=(1 minus sign (119868))
2lowast 119875119871119868 119868
119879119880=
(1 + sign (119868))
2lowast (1 minus 119875
119880) 119868
119881119909119900
= (119875119906
minus 119875119871) sdot
119881dc2
(6)
Case 3 (119875119880
= 1 119875119871
= 1) shorted leg mode
119868119909119899+1
= 119868119909119899exp(minus
119905
119879) (7)
Case 4 (119875119880
= 0 119875119871
= 0) diode bridge mode IGBT switchesoff conditionCase 41 If
((119864119909
+ 119881119873119874
) gt 05119881dc)
119868119863119880
= 119868
119868119879119880
= 0
119881119909119900
=119881dc2
(8)
Case 42 If
((119864119909
+ 119881119873119874
) gt minus05119881dc)
119868119863119880
= 119868
119868119879119880
= 0
119881119909119900
= minus119881dc2
(9)
Case 43 If
(1003816100381610038161003816119864119909 + 119881
119873119874
1003816100381610038161003816 lt 05119881dc)ampamp119868 = 0
119868119863119880
= 0
119868119879119880
= 0
119881119909119900
= 0
(10)
where 119875119880is PWMpulse to upper switch 119875
119871is PWMpulse to
lower switch 119909 are phases (119886) (119887) and (119888) and 119868 is inductionmachine current in (119886) (119887) and (119888) reference frames
Advances in Power Electronics 5
001 002 003 004 005 006 007 008 009 01
0
100
200
300
DC link two-level (IGBT-diode) inverter
minus100
minus200
minus300
V PhA to neutral RTDSV PhA to neutral REF
Time (s)
Van
(V)
Figure 6 Inverter phase A neutral (Van) voltage REF (blue trace)RTDS (red traces)
002 004 006 008 01 012 014 016 018 02
0
10
20
30
40
50
60
Torq
ue (N
m)
DC link two-level (IGBT-diode) inverter
Torque RTDSTorque REF
Time (s)
Applied torque T load
Figure 7 Torque developed REF (blue trace) RTDS (red trace)
The logic for two IGBT switches in phase ldquo119886rdquo is given inwhat follows based on the conditions given previously as perfour different cases
1198791199061198861
= (((Sign (1198681199041198860
) = 1)1003817100381710038171003817 (1198681199041198860
= 0))ampamp
(((05 lowast 119881dc0 minus 11988111989911989900
) ge 0)ampamp
(1198751199061198861
minus 1198751198971198861
) = 1))
1198791198971198861
= (((Sign (1198681199041198860
) = minus1)1003817100381710038171003817 (1198681199041198860
= 0))ampamp
(((minus05 lowast 119881dc0 minus 11988111989911989900
) le 0)ampamp
(1198751199061198861
minus 1198751198971198861
) = minus1))
(11)
Similar logic for other two phases (119887) and (119888) is obtainedby replacing the subscript ldquo119886rdquo in earlier two equations by ldquo119887rdquoand ldquo119888rdquo Switching logic for the diode is explained in detail in[8] and hence has not been given here Similarly switchingfunction logic for IGBT-diode combination from individualIGBT logic and Diode logic is given later for all the switchesin upper legs and lower legs
Phase leg A top switches on (either IGBT or diode)
1198781199061198861
= 1198791199061198861
1003817100381710038171003817 1198631199061198861
1198781198971198861
= 1198791198971198861
1003817100381710038171003817 1198631198971198861
(12)
Phase leg B top switches on (either IGBT or diode)
1198781199061198871
= 1198791199061198871
1003817100381710038171003817 1198631199061198871
1198781198971198871
= 1198791198971198871
1003817100381710038171003817 1198631198971198871
(13)
Phase leg C top switches on (either IGBT or diode)
1198781199061198881
= 1198791199061198881
1003817100381710038171003817 1198631199061198881
1198781198971198881
= 1198791198971198881
1003817100381710038171003817 1198631198971198881
(14)
Phase to DC link midpoint voltage is given by
11988111988601
= 05 lowast 119881dc0 lowast (1198781199061198861
minus 1198781198971198861
)
11988111988701
= 05 lowast 119881dc0 lowast (1198781199061198871
minus 1198781198971198871
)
11988111988801
= 05 lowast 119881dc0 lowast (1198781199061198881
minus 1198781198971198881
)
(15)
Machine side of each phase voltage is given by
1198811198861198991
= (1
3) lowast (2 lowast 119881
11988601minus 11988111988701
minus 11988111988801
)
1198811198871198991
= (1
3) lowast (minus119881
11988601+ 2 lowast 119881
11988701minus 11988111988801
)
1198811198881198991
= (1
3) lowast (minus119881
11988601minus 11988111988701
+ 2 lowast 11988111988801
)
(16)
Voltages 1198811198861198991
1198811198871198991
and 1198811198881198991
in the previously equationare used as an input stator voltage for induction motor Inorder to find the various electrical and mechanical parame-ters like speed flux and current through stator terminals asimplified or reduced order model has to be developed whichhas been explained in detail later
While modelling induction machine the order of thesystem plays an important role in real-time simulation [9]In general induction machine is modelled in two-phasereference frame Sometimes this leads to more state matrixparameters and more computation time At the same timeif it is modelled as the lowest order system then the state
6 Advances in Power Electronics
variables may deviate from its actual values this leads to pooraccuracy and instability In order to compromise betweenaccuracy and computation time the induction machine ismodelled in stationary two-phase reference frame (120572-120573)
which satisfies the previous criteria This model has advan-tages like fewer matrix parameters calculation preservationof symmetry of the induction machine model state matrixand minimization of computation time [9 10]
Induction machine model in 120572-120573 reference frame is asfollows
119889
119889119905119883 (119905) = [119860
119888(120596)] 119883 (119905) + [119861
119888] 119880 (119905)
119884 (119905) = [119862119888] 119883 (119905)
(17)
where the input vector [U(t)] is chosen to be the reference120572-120573 stator voltages [X(t)] is the 120572-120573 stator and rotor fluxstate vector (input) [Y(t)] is the 120572-120573 stator and rotor currentoutput vector (output) and [119860
119888(120596)] [119861
119888] and [119862
119888] are state
matrix input matrix and output matrix respectivelyAs per the reference from [9 10] induction machine
equation in 120572-120573 is expressed in complete form as shown inwhat follows
119889
119889119905
[[[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]]]
]
=
[[[[[[[[[
[
minus119877119904
1205901198711199040
(1 minus 120590) 119877119904
120590119872119904119903
0
0minus119877119904
1205901198711199040
(1 minus 120590) 119877119904
120590119872119904119903
(1 minus 120590)
120590119872119904119903
119877119903 0minus119877119903
120590119871119903minus119901120596
0(1 minus 120590)
120590119872119904119903
119877119903 119901120596minus119877119903
120590119871119903
]]]]]]]]]
]
times
[[[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]]]
]
+
[[[[[
[
1 0
0 1
0 0
0 0
]]]]]
]
[V119904120572
V119904120573
]
[[[
[
119894119904120572
119894119904120573
119894119903120572
119894119903120573
]]]
]
=
[[[[[[[[[[[
[
1
1205901198711199040
minus (1 minus 120590)
120590119872119904119903
0
01
1205901198711199040
minus (1 minus 120590)
120590119872119904119903
minus (1 minus 120590)
120590119872119904119903
01
120590119871119903minus119901120596
0minus (1 minus 120590)
120590119872119904119903
1199011205961
120590119871119903
]]]]]]]]]]]
]
times[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]
]
002 004 006 008 01 012 014 016 018 02
0
20
40
60
80
100
120
140
DC link two-level (IGBT-diode) inverter
Speed radianss RTDSSpeed radianss REF
minus20
Time (s)
Wm
(rad
s)
Figure 8 Rotor speed in rads REF (blue trace) RTDS (red trace)
002 004 006 008 01 012 014 016 018 02
0
10
20
30
40
50
IL-p
hA (A
)DC link two-level (IGBT-diode) inverter
IL-phaseA RTDSIL-phaseA REF
Time (s)
minus10
minus20
minus30
minus40
Figure 9 Stator ph-A current REF (blue trace) RTDS (red trace)
[[[
[
119894119904120572
119894119904120573
120593119903120572
120593119903120573
]]]
]
119899+1
=[[[
[
11989211 11989212 11989213 11989214
11989221 11989222 11989223 11989224
11989231 11989232 11989233 11989234
11989241 11989242 11989243 11989244
]]]
]
times[[[
[
119894119904120572
119894119904120573
120593119903120572
120593119903120573
]]]
]
119899
+[[[
[
ℎ11 ℎ12
ℎ21 ℎ22
ℎ31 ℎ32
ℎ41 ℎ42
]]]
]
[119881119904120572
119881119904120573
]
119899
(18)
where 120590 = 1minus(1198722
119904119903119871119904119871119903) p = no of pole pairs in a machine
and 120596 = speed in rads
Advances in Power Electronics 7
002 004 006 008 01 012 014 016 018 02
0
50
100
150
EMF
phas
e A (V
)DC link two-level (IGBT-diode) inverter
EMF phase A RTDS
minus50
minus100
minus150
Time (s)
Figure 10 Stator ph-A back EMF-REF (blue trace) RTDS (redtrace)
Three-phaseinverter Load
PWM pulses MATLABCode
composerstudio
UncontrolledrectifierAC power
input
DSP1
DSP2
IGBT inverter module-1 IGBT inverter
module-2
RTDS
DSP1
DSP2
UART
DC linkvoltage AC power
output
Figure 11 Block diagram and snapshot of hardware setup
In order to find back emf set 119894119904120572
= 0 and 119894119904120573
= 0 Then119864119904120572
= 119881119904120572 119864119904120573
= 119881119904120573
[119864119904120572
119864119904120573
]
119899
=minus1
(ℎ11 sdot ℎ22 minus ℎ21 sdot ℎ12)[
ℎ22 minusℎ12
minusℎ21 ℎ11]
times [11989213 11989214
11989223 11989224] [
120593119903120572
120593119903120573
]
119899
(19)
ePWM3
WAWB
C280xC28x3xePWM
ePWM2
WAWB
C280xC28x3x
ePWM
ePWM1
WA
WB
C280xC28x3x
ePWM
Sine wave3
Sine wave2
Sine wave1
F28335 eZdsp
Data type conversion2
Uint16
Data type conversion1
Uint16
Data type conversion
Uint16
Figure 12 DSP interface for PWM pulse generation
Table 1 Input parameters for RTDS and Simulink-PLECS
Source parameters DC link inverter Load parametersVm = 1414 lowast 220119891 = 50120596 = 2 lowast pi lowast 119891Rs = 1Ω
Ls = 10mH
Cdc = 10mFFsw = 450Hz119867 = 100119890 minus 6 s
119898 = 08
As given in Table 3
where g119898119899 h119898119899
are the state and input matrix coefficients ofthe stationary reference frame model of induction machineAt every sampling time stator currents have been calculatedusing stator voltages and finally back emf of each phasehas been calculated as per (19) Current sample of back emfhas been used for the next iteration to identify the mode ofoperation of inverter given in Section 3With these equationsa generalized model of the complete electrical drive systemhas been developed and validated with offline Simulink-PLECS model given later
4 Simulation Results
Input parameters for proposedmodel as well as for Simulink-PLECS (REF) offline simulation are shown in Table 1
41 Offline Results versus Real-Time Digital Simulator Inthis case simulations are carried out with both rectifier andinverter now decoupled at DC link Both circuits are treatedas separate circuits and rectifier current with DC link andinverter current with DC link are calculated separately At theend of the iteration DC link voltage will be updated using therectifier and inverter currents
In Figures 4 5 6 7 8 9 and 10 red trace is fromSimulink-PLECS reference results which are overplotted onthat of RTDS-decoupled solution From Figures 4ndash10 it isvery clear that proposed real-timemodel and offline Simulinkresults are matching each other in terms of accuracy as wellas with larger step size of 100120583119904 proposedmodel with the 1120583119904
Simulink reference modelTable 2 shows that at a particular time of sample electrical
and mechanical parameters of real-time electrical drive
8 Advances in Power Electronics
10050
0minus50
minus100018 0185 019 0195 02 0205 021 0215 022 0225
Time (s)
Input phase-phase voltage
Phas
e-ph
ase
volta
ge (V
)
2010
0minus10minus20
Input current (R-phase)
Inpu
t R-p
hase
curr
ent (
A)
018 0185 019 0195 02 0205 021 0215 022 0225Time (s)
(a)
80604020
002 0202 0204 0206 0208 021 0212 0214 0216 0218 022
Time (s)
DC
link
(V)
DC link voltage
201510
50
minus5
DC
link
curr
ent (
A)
02 0202 0204 0206 0208 021 0212 0214 0216 0218 022Time (s)
DC link current
(b)
105
0019 0195 02 0205 021 0215 022 0225 023 0235
Time (s)
Gat
e pul
se (V
) Gate pulses for leg 1
Gate pulses for leg 2
Gate pulses for leg 3
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
Gat
e pul
se (V
)
105
0
105
0
Gat
e pul
se (V
)
(c)
10050
0minus50
minus10002 0205 021 0215 022 0225 023 0235 024 0245
Time (s)
AC output voltagePh
ase-
phas
evo
ltage
(V)
3210
minus1minus2minus3
R-ph
ase c
urre
nt (A
) AC output current (R-phase)
02 0205 021 0215 022 0225 023 0235 024 0245Time (s)
(d)
Figure 13 Proposed mathematical model offline results showing (a) input voltage (ph-ph) and current (R-phase) (b) DC link voltage andcurrent (c) PWM pulses for 3 legs of inverter and (d) output voltage (ph-ph) and current (R-Phase)
Table 2 Comparison of proposed real-time digital simulator results with Simulink-PLECS offline results
S no Parameter Time of sampleReferenceSimulink-PLECS(119886)
Proposed RTDSsolution
(119887)
Percentage of error ()((119887) minus (119886))(119886)
1 DC link voltage V 001 8546 8588 04910102 5001 5009 01
2 Rectifier source current in phase A Amps 0008 1215 1214 minus00820086 2418 2471 219
3 Stator current in phase A Amps 0009512 5195 518 minus000288008951 5596 555 minus000822
4 Inverter line to neutral voltage van (V) 0009512 3333 3333 0008951 3333 3333 0
5 Electromagnetic torque tem (N-m) 001186 6633 6686 0701985 2202 2202 00
6 Rotor speed 120596 (rads) 002 3141 3171 0901922 14848 14851 002
Advances in Power Electronics 9
(a) (b)
(c) (d)
Figure 14 Hardware results from DSP showing (a) input voltage (ph-ph) and current (R-Phase) (b) DC link voltage and current (c) PWMpulses for 3 legs of inverter from DSP and (d) output voltage (ph-ph) and current (R-phase)
systemmodel utilizingAC-DC-AC topology listed previouslyare closelymatchedwith its Simulink reference offline results
5 Real-Time Implementation Using DSP
The given system model is implemented in MATLAB m-file coding and also in real-time hardware setup using theDSP-MATLAB interface PWM are pulses for hardware andMATLAB model generated using DSP processor 2 ePWMmodule is used to generate six pulses at a time from ePWMpins of DSP These pulses are being fed to optocoupler TLP250 which boosts up the voltage level to an extent at whichIGBT switches can be triggered At the same time anotherprocessor is used to run the mathematical model of drivesystem as per decoupled method
Figure 11 represents the block diagram of the hard-ware setup As per specifications given in Appendix A twoSemikron make IGBT IPM module-based inverters used forthis purpose one acts as a rectifier and the other is used as aninverter to drive inductionmotor Pulses fromDSP2 are givento the Semikron inverter module 2 through the optoisolatorICs in order to strengthen the gate drive signal The PWMlogic is developed in Simulink model and Figure 12 showsthe logic generation of bipolar PWM for three-phase inverterComparative results are obtained for the input ph-ph voltageof diode rectifier and input phase current as shown in Figures13(a) and 14(a) Figures 13(b) and 14(b) show DC link voltageand current waveforms
The PWM pulses generated at the output of the optoiso-lator are shown in Figure 14(c) and those from the simulationare shown in Figure 13(c) In Figure 14 all voltage waveformsare phase-phase voltages with the multiplier setting of 200and all current waveforms are phase A current waveforms
with the probe setting at 10mVA Figures 13 and 14(d)reveal that the output voltage between two phases and phasecurrents is closely matched with that of the offline simulationresults As per analytical calculations as well as simulationand hardware results the output RMS voltage obtained acrossthe load is 85V All the parameters are matched except forthe grid voltage and current since it has been assumed as theideal source in simulation model and real grid conditions inthe laboratory are ignored But in practical situations the gridcould be connected to transformers and many other loads inthe laboratory building
6 Conclusion
A new research platform for power electronics and drivesystem modelling using decoupled analytical method hasbeen verified both in offline simulation and in real-timehardware The m-file program developed for state-spacemethod-based electrical drive model accurately matchingwith hardware model The same model has been validatedusing eZdsp processors with one as plant and the other asa controller Decoupled method makes it easier with betteraccuracy and less calculation time which results in fastexecution speed This can be further extended to test thesame with reduced order induction motor model and resultscan be compared with existing results in order to furtherimprovise the real-time model accuracy and its executiontime The results obtained from this work suggest that thedeveloped models using the proposed method can be usedas a research platform and extended to any complex powerelectronic applications The obtained model is flexible andit can be extended to any system with different size (systemorder) These models can be used as user definedfunction
10 Advances in Power Electronics
Table 3 Load specification three-phase induction motor
Parameter Value DescriptionkVAbase 4e3 Rated kVA of the machineVbase 400 Rated voltage (L-L) in (V)Vm 231 lowast radic2 Peak value of AC source voltage (V)119891 50 Rated frequency in Hz120596 2 lowast pi lowast 50 Rated angular frequency in radsRs 1405 Stator resistance in Ω
Ls(Lls + Lm) 0178039 Stator inductance in HRr 1395 Rotor resistance in Ω
Lr(Llr + Lm) 0178039 Rotor inductance in HLm 01722 Stator-rotor mutual inductance in Hℎ 100 Time step in 120583s119899 9 Carrier frequency 119899 times 50Hz119869 00131 Inertia of the machine in kgm2
119861 001841 Friction coefficient in Nmsrad119901 2 No of pole pairs
blocks to test with real-time processorcontroller for futureresearch work
Appendices
A Three-Phase IGBT-Based Inverter(Semikron Make)
IGBT module used SKM75GB123DDC link capacitor 4700 120583FGate driver SKYPER 32 PRO119881dc input 800 (V)119881ac output 415 (V)119868ac output 20 (A)Output frequency 50HzSwitching frequency 10 kHzType of cooling force air cooledTemp 35∘CDuty class class I
B
For more details see Table 3
References
[1] P Livinti and R Pusca ldquoControl of an electric drive system inthe LabVIEWprogramming environmentrdquo inProceedings of the9th International Conference on Remote Engineering and VirtualInstrumentation (REV) pp 1ndash6 Bilbao Spain July 2012
[2] R Champagne L A Dessaint andH Fortin-Blanchette ldquoReal-time simulation of electric drivesrdquoMathematics and Computersin Simulation vol 63 no 3-5 pp 173ndash181 2003
[3] H Eren and C C Fung ldquoVirtual instrumentation of electricdrive systems for automation and testingrdquo in Proceedings ofthe 17th IEEE Instrumentation and Measurement TechnologyConference (IMTC rsquo00) vol 3 pp 1500ndash1505 May 2000
[4] R Champagne L Dessaint G Sybille and B KhodabakhchianldquoApproach for real-time simulation of electric drivesrdquo in Pro-ceedings of the Canadian Conference on Electrical and ComputerEgineering (CCECE rsquo00) vol 1 pp 340ndash344 May 2000
[5] C Bordas C Dufour and O Rudloff ldquoA 3-level neutral-clamped inverter model with natural switching mode sup-port for the real-time simulation of variable speed drivesrdquoin Proceedings of the International Symposium on AdvancedElectromechanical Motion Systems pp 1ndash8 Lille France 2009
[6] A Myaing and V Dinavahi ldquoFPGA-based real-time emulationof power electronic systems with detailed representation ofdevice characteristicsrdquo IEEE Transactions on Industrial Elec-tronics vol 58 no 1 pp 358ndash368 2011
[7] J H Allmeling and W P Hammer ldquoPLECSmdashpiece-wise linearelectrical circuit simulation for Simulinkrdquo in Proceedings of theIEEE International Conference on Power Electronics and DriveSystems (PEDSrsquo99) vol 1 pp 355ndash360 July 1999
[8] S Venugopal and G Narayanan ldquoDesign of FPGA based digitalplatform for control of power electronics systemsrdquo in Proceed-ings of the National Power Electronics Conference pp 1250ndash1255December 2005
[9] K Jayalakshmi and V Ramanarayanan ldquoReal-time simulationof electrical machines on FPGA platformrdquo in Proceedings of theIndia International Conference on Power Electronics (IICPE rsquo06)pp 259ndash263 Chennai India December 2006
[10] R Krishnan Electric Motor Drives Modeling Analysis andControl Pearson Education Asia 2007
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
4 Advances in Power Electronics
are equal (119881dc2 each) Then voltage at the DC link midpointis at zero potential Similarly Ea Eb and Ec are considered tobe back emf of induction machine in each phase and ldquo119873rdquo isthe neutral point of the induction machine stator windingsLet us assume that 119881
1198860 1198811198870 and 119881
1198880are the pole voltages of
each phase legConsider only that phases leg A and P
119880 P119871are the PWM
pulses to upper (T1198801) and lower (T
1198711) IGBT switches If
we define modes of operation for the phase leg A aloneby considering its state variables and PWM sequenceswe arrive at four different examples as given in whatfollows
Case 1 (119875119880
= 1 119875119871
= 0) upper IGBT switches on condition
(((05 sdot 119881dc minus 119864119909) gt 0) ampamp ((119875
119906minus 119875119897) == 1)
100381710038171003817100381710038171003817((119868 lt 0)ampamp((119877119868 + 119871 (
119868 minus 119868119863119906
119867) + 119864119909
+ 119881119873119874
) gt 05119881dc))
119868119879119880
=(1 + sign (119868))
2lowast 119875119880
119868 119868119863119880
=(1 minus sign (119868))
2lowast (1 minus 119875
119871) 119868
119881119909119900
= (119875119906
minus 119875119871) sdot
119881dc2
(5)
Case 2 (119875119880
= 0 119875119871
= 1) lower IGBT switches on condition
(((minus05 sdot 119881dc minus 119864119909) gt 0)ampamp ((119875
119906minus 119875119897) == minus1)
100381710038171003817100381710038171003817((119868 gt 0)ampamp((119877119868 + 119871 (
119868 minus 119868119863119906
119867) + 119864119909
+ 119881119873119874
) gt minus05119881dc))
119868119879119871
=(1 minus sign (119868))
2lowast 119875119871119868 119868
119879119880=
(1 + sign (119868))
2lowast (1 minus 119875
119880) 119868
119881119909119900
= (119875119906
minus 119875119871) sdot
119881dc2
(6)
Case 3 (119875119880
= 1 119875119871
= 1) shorted leg mode
119868119909119899+1
= 119868119909119899exp(minus
119905
119879) (7)
Case 4 (119875119880
= 0 119875119871
= 0) diode bridge mode IGBT switchesoff conditionCase 41 If
((119864119909
+ 119881119873119874
) gt 05119881dc)
119868119863119880
= 119868
119868119879119880
= 0
119881119909119900
=119881dc2
(8)
Case 42 If
((119864119909
+ 119881119873119874
) gt minus05119881dc)
119868119863119880
= 119868
119868119879119880
= 0
119881119909119900
= minus119881dc2
(9)
Case 43 If
(1003816100381610038161003816119864119909 + 119881
119873119874
1003816100381610038161003816 lt 05119881dc)ampamp119868 = 0
119868119863119880
= 0
119868119879119880
= 0
119881119909119900
= 0
(10)
where 119875119880is PWMpulse to upper switch 119875
119871is PWMpulse to
lower switch 119909 are phases (119886) (119887) and (119888) and 119868 is inductionmachine current in (119886) (119887) and (119888) reference frames
Advances in Power Electronics 5
001 002 003 004 005 006 007 008 009 01
0
100
200
300
DC link two-level (IGBT-diode) inverter
minus100
minus200
minus300
V PhA to neutral RTDSV PhA to neutral REF
Time (s)
Van
(V)
Figure 6 Inverter phase A neutral (Van) voltage REF (blue trace)RTDS (red traces)
002 004 006 008 01 012 014 016 018 02
0
10
20
30
40
50
60
Torq
ue (N
m)
DC link two-level (IGBT-diode) inverter
Torque RTDSTorque REF
Time (s)
Applied torque T load
Figure 7 Torque developed REF (blue trace) RTDS (red trace)
The logic for two IGBT switches in phase ldquo119886rdquo is given inwhat follows based on the conditions given previously as perfour different cases
1198791199061198861
= (((Sign (1198681199041198860
) = 1)1003817100381710038171003817 (1198681199041198860
= 0))ampamp
(((05 lowast 119881dc0 minus 11988111989911989900
) ge 0)ampamp
(1198751199061198861
minus 1198751198971198861
) = 1))
1198791198971198861
= (((Sign (1198681199041198860
) = minus1)1003817100381710038171003817 (1198681199041198860
= 0))ampamp
(((minus05 lowast 119881dc0 minus 11988111989911989900
) le 0)ampamp
(1198751199061198861
minus 1198751198971198861
) = minus1))
(11)
Similar logic for other two phases (119887) and (119888) is obtainedby replacing the subscript ldquo119886rdquo in earlier two equations by ldquo119887rdquoand ldquo119888rdquo Switching logic for the diode is explained in detail in[8] and hence has not been given here Similarly switchingfunction logic for IGBT-diode combination from individualIGBT logic and Diode logic is given later for all the switchesin upper legs and lower legs
Phase leg A top switches on (either IGBT or diode)
1198781199061198861
= 1198791199061198861
1003817100381710038171003817 1198631199061198861
1198781198971198861
= 1198791198971198861
1003817100381710038171003817 1198631198971198861
(12)
Phase leg B top switches on (either IGBT or diode)
1198781199061198871
= 1198791199061198871
1003817100381710038171003817 1198631199061198871
1198781198971198871
= 1198791198971198871
1003817100381710038171003817 1198631198971198871
(13)
Phase leg C top switches on (either IGBT or diode)
1198781199061198881
= 1198791199061198881
1003817100381710038171003817 1198631199061198881
1198781198971198881
= 1198791198971198881
1003817100381710038171003817 1198631198971198881
(14)
Phase to DC link midpoint voltage is given by
11988111988601
= 05 lowast 119881dc0 lowast (1198781199061198861
minus 1198781198971198861
)
11988111988701
= 05 lowast 119881dc0 lowast (1198781199061198871
minus 1198781198971198871
)
11988111988801
= 05 lowast 119881dc0 lowast (1198781199061198881
minus 1198781198971198881
)
(15)
Machine side of each phase voltage is given by
1198811198861198991
= (1
3) lowast (2 lowast 119881
11988601minus 11988111988701
minus 11988111988801
)
1198811198871198991
= (1
3) lowast (minus119881
11988601+ 2 lowast 119881
11988701minus 11988111988801
)
1198811198881198991
= (1
3) lowast (minus119881
11988601minus 11988111988701
+ 2 lowast 11988111988801
)
(16)
Voltages 1198811198861198991
1198811198871198991
and 1198811198881198991
in the previously equationare used as an input stator voltage for induction motor Inorder to find the various electrical and mechanical parame-ters like speed flux and current through stator terminals asimplified or reduced order model has to be developed whichhas been explained in detail later
While modelling induction machine the order of thesystem plays an important role in real-time simulation [9]In general induction machine is modelled in two-phasereference frame Sometimes this leads to more state matrixparameters and more computation time At the same timeif it is modelled as the lowest order system then the state
6 Advances in Power Electronics
variables may deviate from its actual values this leads to pooraccuracy and instability In order to compromise betweenaccuracy and computation time the induction machine ismodelled in stationary two-phase reference frame (120572-120573)
which satisfies the previous criteria This model has advan-tages like fewer matrix parameters calculation preservationof symmetry of the induction machine model state matrixand minimization of computation time [9 10]
Induction machine model in 120572-120573 reference frame is asfollows
119889
119889119905119883 (119905) = [119860
119888(120596)] 119883 (119905) + [119861
119888] 119880 (119905)
119884 (119905) = [119862119888] 119883 (119905)
(17)
where the input vector [U(t)] is chosen to be the reference120572-120573 stator voltages [X(t)] is the 120572-120573 stator and rotor fluxstate vector (input) [Y(t)] is the 120572-120573 stator and rotor currentoutput vector (output) and [119860
119888(120596)] [119861
119888] and [119862
119888] are state
matrix input matrix and output matrix respectivelyAs per the reference from [9 10] induction machine
equation in 120572-120573 is expressed in complete form as shown inwhat follows
119889
119889119905
[[[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]]]
]
=
[[[[[[[[[
[
minus119877119904
1205901198711199040
(1 minus 120590) 119877119904
120590119872119904119903
0
0minus119877119904
1205901198711199040
(1 minus 120590) 119877119904
120590119872119904119903
(1 minus 120590)
120590119872119904119903
119877119903 0minus119877119903
120590119871119903minus119901120596
0(1 minus 120590)
120590119872119904119903
119877119903 119901120596minus119877119903
120590119871119903
]]]]]]]]]
]
times
[[[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]]]
]
+
[[[[[
[
1 0
0 1
0 0
0 0
]]]]]
]
[V119904120572
V119904120573
]
[[[
[
119894119904120572
119894119904120573
119894119903120572
119894119903120573
]]]
]
=
[[[[[[[[[[[
[
1
1205901198711199040
minus (1 minus 120590)
120590119872119904119903
0
01
1205901198711199040
minus (1 minus 120590)
120590119872119904119903
minus (1 minus 120590)
120590119872119904119903
01
120590119871119903minus119901120596
0minus (1 minus 120590)
120590119872119904119903
1199011205961
120590119871119903
]]]]]]]]]]]
]
times[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]
]
002 004 006 008 01 012 014 016 018 02
0
20
40
60
80
100
120
140
DC link two-level (IGBT-diode) inverter
Speed radianss RTDSSpeed radianss REF
minus20
Time (s)
Wm
(rad
s)
Figure 8 Rotor speed in rads REF (blue trace) RTDS (red trace)
002 004 006 008 01 012 014 016 018 02
0
10
20
30
40
50
IL-p
hA (A
)DC link two-level (IGBT-diode) inverter
IL-phaseA RTDSIL-phaseA REF
Time (s)
minus10
minus20
minus30
minus40
Figure 9 Stator ph-A current REF (blue trace) RTDS (red trace)
[[[
[
119894119904120572
119894119904120573
120593119903120572
120593119903120573
]]]
]
119899+1
=[[[
[
11989211 11989212 11989213 11989214
11989221 11989222 11989223 11989224
11989231 11989232 11989233 11989234
11989241 11989242 11989243 11989244
]]]
]
times[[[
[
119894119904120572
119894119904120573
120593119903120572
120593119903120573
]]]
]
119899
+[[[
[
ℎ11 ℎ12
ℎ21 ℎ22
ℎ31 ℎ32
ℎ41 ℎ42
]]]
]
[119881119904120572
119881119904120573
]
119899
(18)
where 120590 = 1minus(1198722
119904119903119871119904119871119903) p = no of pole pairs in a machine
and 120596 = speed in rads
Advances in Power Electronics 7
002 004 006 008 01 012 014 016 018 02
0
50
100
150
EMF
phas
e A (V
)DC link two-level (IGBT-diode) inverter
EMF phase A RTDS
minus50
minus100
minus150
Time (s)
Figure 10 Stator ph-A back EMF-REF (blue trace) RTDS (redtrace)
Three-phaseinverter Load
PWM pulses MATLABCode
composerstudio
UncontrolledrectifierAC power
input
DSP1
DSP2
IGBT inverter module-1 IGBT inverter
module-2
RTDS
DSP1
DSP2
UART
DC linkvoltage AC power
output
Figure 11 Block diagram and snapshot of hardware setup
In order to find back emf set 119894119904120572
= 0 and 119894119904120573
= 0 Then119864119904120572
= 119881119904120572 119864119904120573
= 119881119904120573
[119864119904120572
119864119904120573
]
119899
=minus1
(ℎ11 sdot ℎ22 minus ℎ21 sdot ℎ12)[
ℎ22 minusℎ12
minusℎ21 ℎ11]
times [11989213 11989214
11989223 11989224] [
120593119903120572
120593119903120573
]
119899
(19)
ePWM3
WAWB
C280xC28x3xePWM
ePWM2
WAWB
C280xC28x3x
ePWM
ePWM1
WA
WB
C280xC28x3x
ePWM
Sine wave3
Sine wave2
Sine wave1
F28335 eZdsp
Data type conversion2
Uint16
Data type conversion1
Uint16
Data type conversion
Uint16
Figure 12 DSP interface for PWM pulse generation
Table 1 Input parameters for RTDS and Simulink-PLECS
Source parameters DC link inverter Load parametersVm = 1414 lowast 220119891 = 50120596 = 2 lowast pi lowast 119891Rs = 1Ω
Ls = 10mH
Cdc = 10mFFsw = 450Hz119867 = 100119890 minus 6 s
119898 = 08
As given in Table 3
where g119898119899 h119898119899
are the state and input matrix coefficients ofthe stationary reference frame model of induction machineAt every sampling time stator currents have been calculatedusing stator voltages and finally back emf of each phasehas been calculated as per (19) Current sample of back emfhas been used for the next iteration to identify the mode ofoperation of inverter given in Section 3With these equationsa generalized model of the complete electrical drive systemhas been developed and validated with offline Simulink-PLECS model given later
4 Simulation Results
Input parameters for proposedmodel as well as for Simulink-PLECS (REF) offline simulation are shown in Table 1
41 Offline Results versus Real-Time Digital Simulator Inthis case simulations are carried out with both rectifier andinverter now decoupled at DC link Both circuits are treatedas separate circuits and rectifier current with DC link andinverter current with DC link are calculated separately At theend of the iteration DC link voltage will be updated using therectifier and inverter currents
In Figures 4 5 6 7 8 9 and 10 red trace is fromSimulink-PLECS reference results which are overplotted onthat of RTDS-decoupled solution From Figures 4ndash10 it isvery clear that proposed real-timemodel and offline Simulinkresults are matching each other in terms of accuracy as wellas with larger step size of 100120583119904 proposedmodel with the 1120583119904
Simulink reference modelTable 2 shows that at a particular time of sample electrical
and mechanical parameters of real-time electrical drive
8 Advances in Power Electronics
10050
0minus50
minus100018 0185 019 0195 02 0205 021 0215 022 0225
Time (s)
Input phase-phase voltage
Phas
e-ph
ase
volta
ge (V
)
2010
0minus10minus20
Input current (R-phase)
Inpu
t R-p
hase
curr
ent (
A)
018 0185 019 0195 02 0205 021 0215 022 0225Time (s)
(a)
80604020
002 0202 0204 0206 0208 021 0212 0214 0216 0218 022
Time (s)
DC
link
(V)
DC link voltage
201510
50
minus5
DC
link
curr
ent (
A)
02 0202 0204 0206 0208 021 0212 0214 0216 0218 022Time (s)
DC link current
(b)
105
0019 0195 02 0205 021 0215 022 0225 023 0235
Time (s)
Gat
e pul
se (V
) Gate pulses for leg 1
Gate pulses for leg 2
Gate pulses for leg 3
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
Gat
e pul
se (V
)
105
0
105
0
Gat
e pul
se (V
)
(c)
10050
0minus50
minus10002 0205 021 0215 022 0225 023 0235 024 0245
Time (s)
AC output voltagePh
ase-
phas
evo
ltage
(V)
3210
minus1minus2minus3
R-ph
ase c
urre
nt (A
) AC output current (R-phase)
02 0205 021 0215 022 0225 023 0235 024 0245Time (s)
(d)
Figure 13 Proposed mathematical model offline results showing (a) input voltage (ph-ph) and current (R-phase) (b) DC link voltage andcurrent (c) PWM pulses for 3 legs of inverter and (d) output voltage (ph-ph) and current (R-Phase)
Table 2 Comparison of proposed real-time digital simulator results with Simulink-PLECS offline results
S no Parameter Time of sampleReferenceSimulink-PLECS(119886)
Proposed RTDSsolution
(119887)
Percentage of error ()((119887) minus (119886))(119886)
1 DC link voltage V 001 8546 8588 04910102 5001 5009 01
2 Rectifier source current in phase A Amps 0008 1215 1214 minus00820086 2418 2471 219
3 Stator current in phase A Amps 0009512 5195 518 minus000288008951 5596 555 minus000822
4 Inverter line to neutral voltage van (V) 0009512 3333 3333 0008951 3333 3333 0
5 Electromagnetic torque tem (N-m) 001186 6633 6686 0701985 2202 2202 00
6 Rotor speed 120596 (rads) 002 3141 3171 0901922 14848 14851 002
Advances in Power Electronics 9
(a) (b)
(c) (d)
Figure 14 Hardware results from DSP showing (a) input voltage (ph-ph) and current (R-Phase) (b) DC link voltage and current (c) PWMpulses for 3 legs of inverter from DSP and (d) output voltage (ph-ph) and current (R-phase)
systemmodel utilizingAC-DC-AC topology listed previouslyare closelymatchedwith its Simulink reference offline results
5 Real-Time Implementation Using DSP
The given system model is implemented in MATLAB m-file coding and also in real-time hardware setup using theDSP-MATLAB interface PWM are pulses for hardware andMATLAB model generated using DSP processor 2 ePWMmodule is used to generate six pulses at a time from ePWMpins of DSP These pulses are being fed to optocoupler TLP250 which boosts up the voltage level to an extent at whichIGBT switches can be triggered At the same time anotherprocessor is used to run the mathematical model of drivesystem as per decoupled method
Figure 11 represents the block diagram of the hard-ware setup As per specifications given in Appendix A twoSemikron make IGBT IPM module-based inverters used forthis purpose one acts as a rectifier and the other is used as aninverter to drive inductionmotor Pulses fromDSP2 are givento the Semikron inverter module 2 through the optoisolatorICs in order to strengthen the gate drive signal The PWMlogic is developed in Simulink model and Figure 12 showsthe logic generation of bipolar PWM for three-phase inverterComparative results are obtained for the input ph-ph voltageof diode rectifier and input phase current as shown in Figures13(a) and 14(a) Figures 13(b) and 14(b) show DC link voltageand current waveforms
The PWM pulses generated at the output of the optoiso-lator are shown in Figure 14(c) and those from the simulationare shown in Figure 13(c) In Figure 14 all voltage waveformsare phase-phase voltages with the multiplier setting of 200and all current waveforms are phase A current waveforms
with the probe setting at 10mVA Figures 13 and 14(d)reveal that the output voltage between two phases and phasecurrents is closely matched with that of the offline simulationresults As per analytical calculations as well as simulationand hardware results the output RMS voltage obtained acrossthe load is 85V All the parameters are matched except forthe grid voltage and current since it has been assumed as theideal source in simulation model and real grid conditions inthe laboratory are ignored But in practical situations the gridcould be connected to transformers and many other loads inthe laboratory building
6 Conclusion
A new research platform for power electronics and drivesystem modelling using decoupled analytical method hasbeen verified both in offline simulation and in real-timehardware The m-file program developed for state-spacemethod-based electrical drive model accurately matchingwith hardware model The same model has been validatedusing eZdsp processors with one as plant and the other asa controller Decoupled method makes it easier with betteraccuracy and less calculation time which results in fastexecution speed This can be further extended to test thesame with reduced order induction motor model and resultscan be compared with existing results in order to furtherimprovise the real-time model accuracy and its executiontime The results obtained from this work suggest that thedeveloped models using the proposed method can be usedas a research platform and extended to any complex powerelectronic applications The obtained model is flexible andit can be extended to any system with different size (systemorder) These models can be used as user definedfunction
10 Advances in Power Electronics
Table 3 Load specification three-phase induction motor
Parameter Value DescriptionkVAbase 4e3 Rated kVA of the machineVbase 400 Rated voltage (L-L) in (V)Vm 231 lowast radic2 Peak value of AC source voltage (V)119891 50 Rated frequency in Hz120596 2 lowast pi lowast 50 Rated angular frequency in radsRs 1405 Stator resistance in Ω
Ls(Lls + Lm) 0178039 Stator inductance in HRr 1395 Rotor resistance in Ω
Lr(Llr + Lm) 0178039 Rotor inductance in HLm 01722 Stator-rotor mutual inductance in Hℎ 100 Time step in 120583s119899 9 Carrier frequency 119899 times 50Hz119869 00131 Inertia of the machine in kgm2
119861 001841 Friction coefficient in Nmsrad119901 2 No of pole pairs
blocks to test with real-time processorcontroller for futureresearch work
Appendices
A Three-Phase IGBT-Based Inverter(Semikron Make)
IGBT module used SKM75GB123DDC link capacitor 4700 120583FGate driver SKYPER 32 PRO119881dc input 800 (V)119881ac output 415 (V)119868ac output 20 (A)Output frequency 50HzSwitching frequency 10 kHzType of cooling force air cooledTemp 35∘CDuty class class I
B
For more details see Table 3
References
[1] P Livinti and R Pusca ldquoControl of an electric drive system inthe LabVIEWprogramming environmentrdquo inProceedings of the9th International Conference on Remote Engineering and VirtualInstrumentation (REV) pp 1ndash6 Bilbao Spain July 2012
[2] R Champagne L A Dessaint andH Fortin-Blanchette ldquoReal-time simulation of electric drivesrdquoMathematics and Computersin Simulation vol 63 no 3-5 pp 173ndash181 2003
[3] H Eren and C C Fung ldquoVirtual instrumentation of electricdrive systems for automation and testingrdquo in Proceedings ofthe 17th IEEE Instrumentation and Measurement TechnologyConference (IMTC rsquo00) vol 3 pp 1500ndash1505 May 2000
[4] R Champagne L Dessaint G Sybille and B KhodabakhchianldquoApproach for real-time simulation of electric drivesrdquo in Pro-ceedings of the Canadian Conference on Electrical and ComputerEgineering (CCECE rsquo00) vol 1 pp 340ndash344 May 2000
[5] C Bordas C Dufour and O Rudloff ldquoA 3-level neutral-clamped inverter model with natural switching mode sup-port for the real-time simulation of variable speed drivesrdquoin Proceedings of the International Symposium on AdvancedElectromechanical Motion Systems pp 1ndash8 Lille France 2009
[6] A Myaing and V Dinavahi ldquoFPGA-based real-time emulationof power electronic systems with detailed representation ofdevice characteristicsrdquo IEEE Transactions on Industrial Elec-tronics vol 58 no 1 pp 358ndash368 2011
[7] J H Allmeling and W P Hammer ldquoPLECSmdashpiece-wise linearelectrical circuit simulation for Simulinkrdquo in Proceedings of theIEEE International Conference on Power Electronics and DriveSystems (PEDSrsquo99) vol 1 pp 355ndash360 July 1999
[8] S Venugopal and G Narayanan ldquoDesign of FPGA based digitalplatform for control of power electronics systemsrdquo in Proceed-ings of the National Power Electronics Conference pp 1250ndash1255December 2005
[9] K Jayalakshmi and V Ramanarayanan ldquoReal-time simulationof electrical machines on FPGA platformrdquo in Proceedings of theIndia International Conference on Power Electronics (IICPE rsquo06)pp 259ndash263 Chennai India December 2006
[10] R Krishnan Electric Motor Drives Modeling Analysis andControl Pearson Education Asia 2007
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
Advances in Power Electronics 5
001 002 003 004 005 006 007 008 009 01
0
100
200
300
DC link two-level (IGBT-diode) inverter
minus100
minus200
minus300
V PhA to neutral RTDSV PhA to neutral REF
Time (s)
Van
(V)
Figure 6 Inverter phase A neutral (Van) voltage REF (blue trace)RTDS (red traces)
002 004 006 008 01 012 014 016 018 02
0
10
20
30
40
50
60
Torq
ue (N
m)
DC link two-level (IGBT-diode) inverter
Torque RTDSTorque REF
Time (s)
Applied torque T load
Figure 7 Torque developed REF (blue trace) RTDS (red trace)
The logic for two IGBT switches in phase ldquo119886rdquo is given inwhat follows based on the conditions given previously as perfour different cases
1198791199061198861
= (((Sign (1198681199041198860
) = 1)1003817100381710038171003817 (1198681199041198860
= 0))ampamp
(((05 lowast 119881dc0 minus 11988111989911989900
) ge 0)ampamp
(1198751199061198861
minus 1198751198971198861
) = 1))
1198791198971198861
= (((Sign (1198681199041198860
) = minus1)1003817100381710038171003817 (1198681199041198860
= 0))ampamp
(((minus05 lowast 119881dc0 minus 11988111989911989900
) le 0)ampamp
(1198751199061198861
minus 1198751198971198861
) = minus1))
(11)
Similar logic for other two phases (119887) and (119888) is obtainedby replacing the subscript ldquo119886rdquo in earlier two equations by ldquo119887rdquoand ldquo119888rdquo Switching logic for the diode is explained in detail in[8] and hence has not been given here Similarly switchingfunction logic for IGBT-diode combination from individualIGBT logic and Diode logic is given later for all the switchesin upper legs and lower legs
Phase leg A top switches on (either IGBT or diode)
1198781199061198861
= 1198791199061198861
1003817100381710038171003817 1198631199061198861
1198781198971198861
= 1198791198971198861
1003817100381710038171003817 1198631198971198861
(12)
Phase leg B top switches on (either IGBT or diode)
1198781199061198871
= 1198791199061198871
1003817100381710038171003817 1198631199061198871
1198781198971198871
= 1198791198971198871
1003817100381710038171003817 1198631198971198871
(13)
Phase leg C top switches on (either IGBT or diode)
1198781199061198881
= 1198791199061198881
1003817100381710038171003817 1198631199061198881
1198781198971198881
= 1198791198971198881
1003817100381710038171003817 1198631198971198881
(14)
Phase to DC link midpoint voltage is given by
11988111988601
= 05 lowast 119881dc0 lowast (1198781199061198861
minus 1198781198971198861
)
11988111988701
= 05 lowast 119881dc0 lowast (1198781199061198871
minus 1198781198971198871
)
11988111988801
= 05 lowast 119881dc0 lowast (1198781199061198881
minus 1198781198971198881
)
(15)
Machine side of each phase voltage is given by
1198811198861198991
= (1
3) lowast (2 lowast 119881
11988601minus 11988111988701
minus 11988111988801
)
1198811198871198991
= (1
3) lowast (minus119881
11988601+ 2 lowast 119881
11988701minus 11988111988801
)
1198811198881198991
= (1
3) lowast (minus119881
11988601minus 11988111988701
+ 2 lowast 11988111988801
)
(16)
Voltages 1198811198861198991
1198811198871198991
and 1198811198881198991
in the previously equationare used as an input stator voltage for induction motor Inorder to find the various electrical and mechanical parame-ters like speed flux and current through stator terminals asimplified or reduced order model has to be developed whichhas been explained in detail later
While modelling induction machine the order of thesystem plays an important role in real-time simulation [9]In general induction machine is modelled in two-phasereference frame Sometimes this leads to more state matrixparameters and more computation time At the same timeif it is modelled as the lowest order system then the state
6 Advances in Power Electronics
variables may deviate from its actual values this leads to pooraccuracy and instability In order to compromise betweenaccuracy and computation time the induction machine ismodelled in stationary two-phase reference frame (120572-120573)
which satisfies the previous criteria This model has advan-tages like fewer matrix parameters calculation preservationof symmetry of the induction machine model state matrixand minimization of computation time [9 10]
Induction machine model in 120572-120573 reference frame is asfollows
119889
119889119905119883 (119905) = [119860
119888(120596)] 119883 (119905) + [119861
119888] 119880 (119905)
119884 (119905) = [119862119888] 119883 (119905)
(17)
where the input vector [U(t)] is chosen to be the reference120572-120573 stator voltages [X(t)] is the 120572-120573 stator and rotor fluxstate vector (input) [Y(t)] is the 120572-120573 stator and rotor currentoutput vector (output) and [119860
119888(120596)] [119861
119888] and [119862
119888] are state
matrix input matrix and output matrix respectivelyAs per the reference from [9 10] induction machine
equation in 120572-120573 is expressed in complete form as shown inwhat follows
119889
119889119905
[[[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]]]
]
=
[[[[[[[[[
[
minus119877119904
1205901198711199040
(1 minus 120590) 119877119904
120590119872119904119903
0
0minus119877119904
1205901198711199040
(1 minus 120590) 119877119904
120590119872119904119903
(1 minus 120590)
120590119872119904119903
119877119903 0minus119877119903
120590119871119903minus119901120596
0(1 minus 120590)
120590119872119904119903
119877119903 119901120596minus119877119903
120590119871119903
]]]]]]]]]
]
times
[[[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]]]
]
+
[[[[[
[
1 0
0 1
0 0
0 0
]]]]]
]
[V119904120572
V119904120573
]
[[[
[
119894119904120572
119894119904120573
119894119903120572
119894119903120573
]]]
]
=
[[[[[[[[[[[
[
1
1205901198711199040
minus (1 minus 120590)
120590119872119904119903
0
01
1205901198711199040
minus (1 minus 120590)
120590119872119904119903
minus (1 minus 120590)
120590119872119904119903
01
120590119871119903minus119901120596
0minus (1 minus 120590)
120590119872119904119903
1199011205961
120590119871119903
]]]]]]]]]]]
]
times[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]
]
002 004 006 008 01 012 014 016 018 02
0
20
40
60
80
100
120
140
DC link two-level (IGBT-diode) inverter
Speed radianss RTDSSpeed radianss REF
minus20
Time (s)
Wm
(rad
s)
Figure 8 Rotor speed in rads REF (blue trace) RTDS (red trace)
002 004 006 008 01 012 014 016 018 02
0
10
20
30
40
50
IL-p
hA (A
)DC link two-level (IGBT-diode) inverter
IL-phaseA RTDSIL-phaseA REF
Time (s)
minus10
minus20
minus30
minus40
Figure 9 Stator ph-A current REF (blue trace) RTDS (red trace)
[[[
[
119894119904120572
119894119904120573
120593119903120572
120593119903120573
]]]
]
119899+1
=[[[
[
11989211 11989212 11989213 11989214
11989221 11989222 11989223 11989224
11989231 11989232 11989233 11989234
11989241 11989242 11989243 11989244
]]]
]
times[[[
[
119894119904120572
119894119904120573
120593119903120572
120593119903120573
]]]
]
119899
+[[[
[
ℎ11 ℎ12
ℎ21 ℎ22
ℎ31 ℎ32
ℎ41 ℎ42
]]]
]
[119881119904120572
119881119904120573
]
119899
(18)
where 120590 = 1minus(1198722
119904119903119871119904119871119903) p = no of pole pairs in a machine
and 120596 = speed in rads
Advances in Power Electronics 7
002 004 006 008 01 012 014 016 018 02
0
50
100
150
EMF
phas
e A (V
)DC link two-level (IGBT-diode) inverter
EMF phase A RTDS
minus50
minus100
minus150
Time (s)
Figure 10 Stator ph-A back EMF-REF (blue trace) RTDS (redtrace)
Three-phaseinverter Load
PWM pulses MATLABCode
composerstudio
UncontrolledrectifierAC power
input
DSP1
DSP2
IGBT inverter module-1 IGBT inverter
module-2
RTDS
DSP1
DSP2
UART
DC linkvoltage AC power
output
Figure 11 Block diagram and snapshot of hardware setup
In order to find back emf set 119894119904120572
= 0 and 119894119904120573
= 0 Then119864119904120572
= 119881119904120572 119864119904120573
= 119881119904120573
[119864119904120572
119864119904120573
]
119899
=minus1
(ℎ11 sdot ℎ22 minus ℎ21 sdot ℎ12)[
ℎ22 minusℎ12
minusℎ21 ℎ11]
times [11989213 11989214
11989223 11989224] [
120593119903120572
120593119903120573
]
119899
(19)
ePWM3
WAWB
C280xC28x3xePWM
ePWM2
WAWB
C280xC28x3x
ePWM
ePWM1
WA
WB
C280xC28x3x
ePWM
Sine wave3
Sine wave2
Sine wave1
F28335 eZdsp
Data type conversion2
Uint16
Data type conversion1
Uint16
Data type conversion
Uint16
Figure 12 DSP interface for PWM pulse generation
Table 1 Input parameters for RTDS and Simulink-PLECS
Source parameters DC link inverter Load parametersVm = 1414 lowast 220119891 = 50120596 = 2 lowast pi lowast 119891Rs = 1Ω
Ls = 10mH
Cdc = 10mFFsw = 450Hz119867 = 100119890 minus 6 s
119898 = 08
As given in Table 3
where g119898119899 h119898119899
are the state and input matrix coefficients ofthe stationary reference frame model of induction machineAt every sampling time stator currents have been calculatedusing stator voltages and finally back emf of each phasehas been calculated as per (19) Current sample of back emfhas been used for the next iteration to identify the mode ofoperation of inverter given in Section 3With these equationsa generalized model of the complete electrical drive systemhas been developed and validated with offline Simulink-PLECS model given later
4 Simulation Results
Input parameters for proposedmodel as well as for Simulink-PLECS (REF) offline simulation are shown in Table 1
41 Offline Results versus Real-Time Digital Simulator Inthis case simulations are carried out with both rectifier andinverter now decoupled at DC link Both circuits are treatedas separate circuits and rectifier current with DC link andinverter current with DC link are calculated separately At theend of the iteration DC link voltage will be updated using therectifier and inverter currents
In Figures 4 5 6 7 8 9 and 10 red trace is fromSimulink-PLECS reference results which are overplotted onthat of RTDS-decoupled solution From Figures 4ndash10 it isvery clear that proposed real-timemodel and offline Simulinkresults are matching each other in terms of accuracy as wellas with larger step size of 100120583119904 proposedmodel with the 1120583119904
Simulink reference modelTable 2 shows that at a particular time of sample electrical
and mechanical parameters of real-time electrical drive
8 Advances in Power Electronics
10050
0minus50
minus100018 0185 019 0195 02 0205 021 0215 022 0225
Time (s)
Input phase-phase voltage
Phas
e-ph
ase
volta
ge (V
)
2010
0minus10minus20
Input current (R-phase)
Inpu
t R-p
hase
curr
ent (
A)
018 0185 019 0195 02 0205 021 0215 022 0225Time (s)
(a)
80604020
002 0202 0204 0206 0208 021 0212 0214 0216 0218 022
Time (s)
DC
link
(V)
DC link voltage
201510
50
minus5
DC
link
curr
ent (
A)
02 0202 0204 0206 0208 021 0212 0214 0216 0218 022Time (s)
DC link current
(b)
105
0019 0195 02 0205 021 0215 022 0225 023 0235
Time (s)
Gat
e pul
se (V
) Gate pulses for leg 1
Gate pulses for leg 2
Gate pulses for leg 3
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
Gat
e pul
se (V
)
105
0
105
0
Gat
e pul
se (V
)
(c)
10050
0minus50
minus10002 0205 021 0215 022 0225 023 0235 024 0245
Time (s)
AC output voltagePh
ase-
phas
evo
ltage
(V)
3210
minus1minus2minus3
R-ph
ase c
urre
nt (A
) AC output current (R-phase)
02 0205 021 0215 022 0225 023 0235 024 0245Time (s)
(d)
Figure 13 Proposed mathematical model offline results showing (a) input voltage (ph-ph) and current (R-phase) (b) DC link voltage andcurrent (c) PWM pulses for 3 legs of inverter and (d) output voltage (ph-ph) and current (R-Phase)
Table 2 Comparison of proposed real-time digital simulator results with Simulink-PLECS offline results
S no Parameter Time of sampleReferenceSimulink-PLECS(119886)
Proposed RTDSsolution
(119887)
Percentage of error ()((119887) minus (119886))(119886)
1 DC link voltage V 001 8546 8588 04910102 5001 5009 01
2 Rectifier source current in phase A Amps 0008 1215 1214 minus00820086 2418 2471 219
3 Stator current in phase A Amps 0009512 5195 518 minus000288008951 5596 555 minus000822
4 Inverter line to neutral voltage van (V) 0009512 3333 3333 0008951 3333 3333 0
5 Electromagnetic torque tem (N-m) 001186 6633 6686 0701985 2202 2202 00
6 Rotor speed 120596 (rads) 002 3141 3171 0901922 14848 14851 002
Advances in Power Electronics 9
(a) (b)
(c) (d)
Figure 14 Hardware results from DSP showing (a) input voltage (ph-ph) and current (R-Phase) (b) DC link voltage and current (c) PWMpulses for 3 legs of inverter from DSP and (d) output voltage (ph-ph) and current (R-phase)
systemmodel utilizingAC-DC-AC topology listed previouslyare closelymatchedwith its Simulink reference offline results
5 Real-Time Implementation Using DSP
The given system model is implemented in MATLAB m-file coding and also in real-time hardware setup using theDSP-MATLAB interface PWM are pulses for hardware andMATLAB model generated using DSP processor 2 ePWMmodule is used to generate six pulses at a time from ePWMpins of DSP These pulses are being fed to optocoupler TLP250 which boosts up the voltage level to an extent at whichIGBT switches can be triggered At the same time anotherprocessor is used to run the mathematical model of drivesystem as per decoupled method
Figure 11 represents the block diagram of the hard-ware setup As per specifications given in Appendix A twoSemikron make IGBT IPM module-based inverters used forthis purpose one acts as a rectifier and the other is used as aninverter to drive inductionmotor Pulses fromDSP2 are givento the Semikron inverter module 2 through the optoisolatorICs in order to strengthen the gate drive signal The PWMlogic is developed in Simulink model and Figure 12 showsthe logic generation of bipolar PWM for three-phase inverterComparative results are obtained for the input ph-ph voltageof diode rectifier and input phase current as shown in Figures13(a) and 14(a) Figures 13(b) and 14(b) show DC link voltageand current waveforms
The PWM pulses generated at the output of the optoiso-lator are shown in Figure 14(c) and those from the simulationare shown in Figure 13(c) In Figure 14 all voltage waveformsare phase-phase voltages with the multiplier setting of 200and all current waveforms are phase A current waveforms
with the probe setting at 10mVA Figures 13 and 14(d)reveal that the output voltage between two phases and phasecurrents is closely matched with that of the offline simulationresults As per analytical calculations as well as simulationand hardware results the output RMS voltage obtained acrossthe load is 85V All the parameters are matched except forthe grid voltage and current since it has been assumed as theideal source in simulation model and real grid conditions inthe laboratory are ignored But in practical situations the gridcould be connected to transformers and many other loads inthe laboratory building
6 Conclusion
A new research platform for power electronics and drivesystem modelling using decoupled analytical method hasbeen verified both in offline simulation and in real-timehardware The m-file program developed for state-spacemethod-based electrical drive model accurately matchingwith hardware model The same model has been validatedusing eZdsp processors with one as plant and the other asa controller Decoupled method makes it easier with betteraccuracy and less calculation time which results in fastexecution speed This can be further extended to test thesame with reduced order induction motor model and resultscan be compared with existing results in order to furtherimprovise the real-time model accuracy and its executiontime The results obtained from this work suggest that thedeveloped models using the proposed method can be usedas a research platform and extended to any complex powerelectronic applications The obtained model is flexible andit can be extended to any system with different size (systemorder) These models can be used as user definedfunction
10 Advances in Power Electronics
Table 3 Load specification three-phase induction motor
Parameter Value DescriptionkVAbase 4e3 Rated kVA of the machineVbase 400 Rated voltage (L-L) in (V)Vm 231 lowast radic2 Peak value of AC source voltage (V)119891 50 Rated frequency in Hz120596 2 lowast pi lowast 50 Rated angular frequency in radsRs 1405 Stator resistance in Ω
Ls(Lls + Lm) 0178039 Stator inductance in HRr 1395 Rotor resistance in Ω
Lr(Llr + Lm) 0178039 Rotor inductance in HLm 01722 Stator-rotor mutual inductance in Hℎ 100 Time step in 120583s119899 9 Carrier frequency 119899 times 50Hz119869 00131 Inertia of the machine in kgm2
119861 001841 Friction coefficient in Nmsrad119901 2 No of pole pairs
blocks to test with real-time processorcontroller for futureresearch work
Appendices
A Three-Phase IGBT-Based Inverter(Semikron Make)
IGBT module used SKM75GB123DDC link capacitor 4700 120583FGate driver SKYPER 32 PRO119881dc input 800 (V)119881ac output 415 (V)119868ac output 20 (A)Output frequency 50HzSwitching frequency 10 kHzType of cooling force air cooledTemp 35∘CDuty class class I
B
For more details see Table 3
References
[1] P Livinti and R Pusca ldquoControl of an electric drive system inthe LabVIEWprogramming environmentrdquo inProceedings of the9th International Conference on Remote Engineering and VirtualInstrumentation (REV) pp 1ndash6 Bilbao Spain July 2012
[2] R Champagne L A Dessaint andH Fortin-Blanchette ldquoReal-time simulation of electric drivesrdquoMathematics and Computersin Simulation vol 63 no 3-5 pp 173ndash181 2003
[3] H Eren and C C Fung ldquoVirtual instrumentation of electricdrive systems for automation and testingrdquo in Proceedings ofthe 17th IEEE Instrumentation and Measurement TechnologyConference (IMTC rsquo00) vol 3 pp 1500ndash1505 May 2000
[4] R Champagne L Dessaint G Sybille and B KhodabakhchianldquoApproach for real-time simulation of electric drivesrdquo in Pro-ceedings of the Canadian Conference on Electrical and ComputerEgineering (CCECE rsquo00) vol 1 pp 340ndash344 May 2000
[5] C Bordas C Dufour and O Rudloff ldquoA 3-level neutral-clamped inverter model with natural switching mode sup-port for the real-time simulation of variable speed drivesrdquoin Proceedings of the International Symposium on AdvancedElectromechanical Motion Systems pp 1ndash8 Lille France 2009
[6] A Myaing and V Dinavahi ldquoFPGA-based real-time emulationof power electronic systems with detailed representation ofdevice characteristicsrdquo IEEE Transactions on Industrial Elec-tronics vol 58 no 1 pp 358ndash368 2011
[7] J H Allmeling and W P Hammer ldquoPLECSmdashpiece-wise linearelectrical circuit simulation for Simulinkrdquo in Proceedings of theIEEE International Conference on Power Electronics and DriveSystems (PEDSrsquo99) vol 1 pp 355ndash360 July 1999
[8] S Venugopal and G Narayanan ldquoDesign of FPGA based digitalplatform for control of power electronics systemsrdquo in Proceed-ings of the National Power Electronics Conference pp 1250ndash1255December 2005
[9] K Jayalakshmi and V Ramanarayanan ldquoReal-time simulationof electrical machines on FPGA platformrdquo in Proceedings of theIndia International Conference on Power Electronics (IICPE rsquo06)pp 259ndash263 Chennai India December 2006
[10] R Krishnan Electric Motor Drives Modeling Analysis andControl Pearson Education Asia 2007
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
6 Advances in Power Electronics
variables may deviate from its actual values this leads to pooraccuracy and instability In order to compromise betweenaccuracy and computation time the induction machine ismodelled in stationary two-phase reference frame (120572-120573)
which satisfies the previous criteria This model has advan-tages like fewer matrix parameters calculation preservationof symmetry of the induction machine model state matrixand minimization of computation time [9 10]
Induction machine model in 120572-120573 reference frame is asfollows
119889
119889119905119883 (119905) = [119860
119888(120596)] 119883 (119905) + [119861
119888] 119880 (119905)
119884 (119905) = [119862119888] 119883 (119905)
(17)
where the input vector [U(t)] is chosen to be the reference120572-120573 stator voltages [X(t)] is the 120572-120573 stator and rotor fluxstate vector (input) [Y(t)] is the 120572-120573 stator and rotor currentoutput vector (output) and [119860
119888(120596)] [119861
119888] and [119862
119888] are state
matrix input matrix and output matrix respectivelyAs per the reference from [9 10] induction machine
equation in 120572-120573 is expressed in complete form as shown inwhat follows
119889
119889119905
[[[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]]]
]
=
[[[[[[[[[
[
minus119877119904
1205901198711199040
(1 minus 120590) 119877119904
120590119872119904119903
0
0minus119877119904
1205901198711199040
(1 minus 120590) 119877119904
120590119872119904119903
(1 minus 120590)
120590119872119904119903
119877119903 0minus119877119903
120590119871119903minus119901120596
0(1 minus 120590)
120590119872119904119903
119877119903 119901120596minus119877119903
120590119871119903
]]]]]]]]]
]
times
[[[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]]]
]
+
[[[[[
[
1 0
0 1
0 0
0 0
]]]]]
]
[V119904120572
V119904120573
]
[[[
[
119894119904120572
119894119904120573
119894119903120572
119894119903120573
]]]
]
=
[[[[[[[[[[[
[
1
1205901198711199040
minus (1 minus 120590)
120590119872119904119903
0
01
1205901198711199040
minus (1 minus 120590)
120590119872119904119903
minus (1 minus 120590)
120590119872119904119903
01
120590119871119903minus119901120596
0minus (1 minus 120590)
120590119872119904119903
1199011205961
120590119871119903
]]]]]]]]]]]
]
times[[[
[
120593119904120572
120593119904120573
120593119903120572
120593119903120573
]]]
]
002 004 006 008 01 012 014 016 018 02
0
20
40
60
80
100
120
140
DC link two-level (IGBT-diode) inverter
Speed radianss RTDSSpeed radianss REF
minus20
Time (s)
Wm
(rad
s)
Figure 8 Rotor speed in rads REF (blue trace) RTDS (red trace)
002 004 006 008 01 012 014 016 018 02
0
10
20
30
40
50
IL-p
hA (A
)DC link two-level (IGBT-diode) inverter
IL-phaseA RTDSIL-phaseA REF
Time (s)
minus10
minus20
minus30
minus40
Figure 9 Stator ph-A current REF (blue trace) RTDS (red trace)
[[[
[
119894119904120572
119894119904120573
120593119903120572
120593119903120573
]]]
]
119899+1
=[[[
[
11989211 11989212 11989213 11989214
11989221 11989222 11989223 11989224
11989231 11989232 11989233 11989234
11989241 11989242 11989243 11989244
]]]
]
times[[[
[
119894119904120572
119894119904120573
120593119903120572
120593119903120573
]]]
]
119899
+[[[
[
ℎ11 ℎ12
ℎ21 ℎ22
ℎ31 ℎ32
ℎ41 ℎ42
]]]
]
[119881119904120572
119881119904120573
]
119899
(18)
where 120590 = 1minus(1198722
119904119903119871119904119871119903) p = no of pole pairs in a machine
and 120596 = speed in rads
Advances in Power Electronics 7
002 004 006 008 01 012 014 016 018 02
0
50
100
150
EMF
phas
e A (V
)DC link two-level (IGBT-diode) inverter
EMF phase A RTDS
minus50
minus100
minus150
Time (s)
Figure 10 Stator ph-A back EMF-REF (blue trace) RTDS (redtrace)
Three-phaseinverter Load
PWM pulses MATLABCode
composerstudio
UncontrolledrectifierAC power
input
DSP1
DSP2
IGBT inverter module-1 IGBT inverter
module-2
RTDS
DSP1
DSP2
UART
DC linkvoltage AC power
output
Figure 11 Block diagram and snapshot of hardware setup
In order to find back emf set 119894119904120572
= 0 and 119894119904120573
= 0 Then119864119904120572
= 119881119904120572 119864119904120573
= 119881119904120573
[119864119904120572
119864119904120573
]
119899
=minus1
(ℎ11 sdot ℎ22 minus ℎ21 sdot ℎ12)[
ℎ22 minusℎ12
minusℎ21 ℎ11]
times [11989213 11989214
11989223 11989224] [
120593119903120572
120593119903120573
]
119899
(19)
ePWM3
WAWB
C280xC28x3xePWM
ePWM2
WAWB
C280xC28x3x
ePWM
ePWM1
WA
WB
C280xC28x3x
ePWM
Sine wave3
Sine wave2
Sine wave1
F28335 eZdsp
Data type conversion2
Uint16
Data type conversion1
Uint16
Data type conversion
Uint16
Figure 12 DSP interface for PWM pulse generation
Table 1 Input parameters for RTDS and Simulink-PLECS
Source parameters DC link inverter Load parametersVm = 1414 lowast 220119891 = 50120596 = 2 lowast pi lowast 119891Rs = 1Ω
Ls = 10mH
Cdc = 10mFFsw = 450Hz119867 = 100119890 minus 6 s
119898 = 08
As given in Table 3
where g119898119899 h119898119899
are the state and input matrix coefficients ofthe stationary reference frame model of induction machineAt every sampling time stator currents have been calculatedusing stator voltages and finally back emf of each phasehas been calculated as per (19) Current sample of back emfhas been used for the next iteration to identify the mode ofoperation of inverter given in Section 3With these equationsa generalized model of the complete electrical drive systemhas been developed and validated with offline Simulink-PLECS model given later
4 Simulation Results
Input parameters for proposedmodel as well as for Simulink-PLECS (REF) offline simulation are shown in Table 1
41 Offline Results versus Real-Time Digital Simulator Inthis case simulations are carried out with both rectifier andinverter now decoupled at DC link Both circuits are treatedas separate circuits and rectifier current with DC link andinverter current with DC link are calculated separately At theend of the iteration DC link voltage will be updated using therectifier and inverter currents
In Figures 4 5 6 7 8 9 and 10 red trace is fromSimulink-PLECS reference results which are overplotted onthat of RTDS-decoupled solution From Figures 4ndash10 it isvery clear that proposed real-timemodel and offline Simulinkresults are matching each other in terms of accuracy as wellas with larger step size of 100120583119904 proposedmodel with the 1120583119904
Simulink reference modelTable 2 shows that at a particular time of sample electrical
and mechanical parameters of real-time electrical drive
8 Advances in Power Electronics
10050
0minus50
minus100018 0185 019 0195 02 0205 021 0215 022 0225
Time (s)
Input phase-phase voltage
Phas
e-ph
ase
volta
ge (V
)
2010
0minus10minus20
Input current (R-phase)
Inpu
t R-p
hase
curr
ent (
A)
018 0185 019 0195 02 0205 021 0215 022 0225Time (s)
(a)
80604020
002 0202 0204 0206 0208 021 0212 0214 0216 0218 022
Time (s)
DC
link
(V)
DC link voltage
201510
50
minus5
DC
link
curr
ent (
A)
02 0202 0204 0206 0208 021 0212 0214 0216 0218 022Time (s)
DC link current
(b)
105
0019 0195 02 0205 021 0215 022 0225 023 0235
Time (s)
Gat
e pul
se (V
) Gate pulses for leg 1
Gate pulses for leg 2
Gate pulses for leg 3
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
Gat
e pul
se (V
)
105
0
105
0
Gat
e pul
se (V
)
(c)
10050
0minus50
minus10002 0205 021 0215 022 0225 023 0235 024 0245
Time (s)
AC output voltagePh
ase-
phas
evo
ltage
(V)
3210
minus1minus2minus3
R-ph
ase c
urre
nt (A
) AC output current (R-phase)
02 0205 021 0215 022 0225 023 0235 024 0245Time (s)
(d)
Figure 13 Proposed mathematical model offline results showing (a) input voltage (ph-ph) and current (R-phase) (b) DC link voltage andcurrent (c) PWM pulses for 3 legs of inverter and (d) output voltage (ph-ph) and current (R-Phase)
Table 2 Comparison of proposed real-time digital simulator results with Simulink-PLECS offline results
S no Parameter Time of sampleReferenceSimulink-PLECS(119886)
Proposed RTDSsolution
(119887)
Percentage of error ()((119887) minus (119886))(119886)
1 DC link voltage V 001 8546 8588 04910102 5001 5009 01
2 Rectifier source current in phase A Amps 0008 1215 1214 minus00820086 2418 2471 219
3 Stator current in phase A Amps 0009512 5195 518 minus000288008951 5596 555 minus000822
4 Inverter line to neutral voltage van (V) 0009512 3333 3333 0008951 3333 3333 0
5 Electromagnetic torque tem (N-m) 001186 6633 6686 0701985 2202 2202 00
6 Rotor speed 120596 (rads) 002 3141 3171 0901922 14848 14851 002
Advances in Power Electronics 9
(a) (b)
(c) (d)
Figure 14 Hardware results from DSP showing (a) input voltage (ph-ph) and current (R-Phase) (b) DC link voltage and current (c) PWMpulses for 3 legs of inverter from DSP and (d) output voltage (ph-ph) and current (R-phase)
systemmodel utilizingAC-DC-AC topology listed previouslyare closelymatchedwith its Simulink reference offline results
5 Real-Time Implementation Using DSP
The given system model is implemented in MATLAB m-file coding and also in real-time hardware setup using theDSP-MATLAB interface PWM are pulses for hardware andMATLAB model generated using DSP processor 2 ePWMmodule is used to generate six pulses at a time from ePWMpins of DSP These pulses are being fed to optocoupler TLP250 which boosts up the voltage level to an extent at whichIGBT switches can be triggered At the same time anotherprocessor is used to run the mathematical model of drivesystem as per decoupled method
Figure 11 represents the block diagram of the hard-ware setup As per specifications given in Appendix A twoSemikron make IGBT IPM module-based inverters used forthis purpose one acts as a rectifier and the other is used as aninverter to drive inductionmotor Pulses fromDSP2 are givento the Semikron inverter module 2 through the optoisolatorICs in order to strengthen the gate drive signal The PWMlogic is developed in Simulink model and Figure 12 showsthe logic generation of bipolar PWM for three-phase inverterComparative results are obtained for the input ph-ph voltageof diode rectifier and input phase current as shown in Figures13(a) and 14(a) Figures 13(b) and 14(b) show DC link voltageand current waveforms
The PWM pulses generated at the output of the optoiso-lator are shown in Figure 14(c) and those from the simulationare shown in Figure 13(c) In Figure 14 all voltage waveformsare phase-phase voltages with the multiplier setting of 200and all current waveforms are phase A current waveforms
with the probe setting at 10mVA Figures 13 and 14(d)reveal that the output voltage between two phases and phasecurrents is closely matched with that of the offline simulationresults As per analytical calculations as well as simulationand hardware results the output RMS voltage obtained acrossthe load is 85V All the parameters are matched except forthe grid voltage and current since it has been assumed as theideal source in simulation model and real grid conditions inthe laboratory are ignored But in practical situations the gridcould be connected to transformers and many other loads inthe laboratory building
6 Conclusion
A new research platform for power electronics and drivesystem modelling using decoupled analytical method hasbeen verified both in offline simulation and in real-timehardware The m-file program developed for state-spacemethod-based electrical drive model accurately matchingwith hardware model The same model has been validatedusing eZdsp processors with one as plant and the other asa controller Decoupled method makes it easier with betteraccuracy and less calculation time which results in fastexecution speed This can be further extended to test thesame with reduced order induction motor model and resultscan be compared with existing results in order to furtherimprovise the real-time model accuracy and its executiontime The results obtained from this work suggest that thedeveloped models using the proposed method can be usedas a research platform and extended to any complex powerelectronic applications The obtained model is flexible andit can be extended to any system with different size (systemorder) These models can be used as user definedfunction
10 Advances in Power Electronics
Table 3 Load specification three-phase induction motor
Parameter Value DescriptionkVAbase 4e3 Rated kVA of the machineVbase 400 Rated voltage (L-L) in (V)Vm 231 lowast radic2 Peak value of AC source voltage (V)119891 50 Rated frequency in Hz120596 2 lowast pi lowast 50 Rated angular frequency in radsRs 1405 Stator resistance in Ω
Ls(Lls + Lm) 0178039 Stator inductance in HRr 1395 Rotor resistance in Ω
Lr(Llr + Lm) 0178039 Rotor inductance in HLm 01722 Stator-rotor mutual inductance in Hℎ 100 Time step in 120583s119899 9 Carrier frequency 119899 times 50Hz119869 00131 Inertia of the machine in kgm2
119861 001841 Friction coefficient in Nmsrad119901 2 No of pole pairs
blocks to test with real-time processorcontroller for futureresearch work
Appendices
A Three-Phase IGBT-Based Inverter(Semikron Make)
IGBT module used SKM75GB123DDC link capacitor 4700 120583FGate driver SKYPER 32 PRO119881dc input 800 (V)119881ac output 415 (V)119868ac output 20 (A)Output frequency 50HzSwitching frequency 10 kHzType of cooling force air cooledTemp 35∘CDuty class class I
B
For more details see Table 3
References
[1] P Livinti and R Pusca ldquoControl of an electric drive system inthe LabVIEWprogramming environmentrdquo inProceedings of the9th International Conference on Remote Engineering and VirtualInstrumentation (REV) pp 1ndash6 Bilbao Spain July 2012
[2] R Champagne L A Dessaint andH Fortin-Blanchette ldquoReal-time simulation of electric drivesrdquoMathematics and Computersin Simulation vol 63 no 3-5 pp 173ndash181 2003
[3] H Eren and C C Fung ldquoVirtual instrumentation of electricdrive systems for automation and testingrdquo in Proceedings ofthe 17th IEEE Instrumentation and Measurement TechnologyConference (IMTC rsquo00) vol 3 pp 1500ndash1505 May 2000
[4] R Champagne L Dessaint G Sybille and B KhodabakhchianldquoApproach for real-time simulation of electric drivesrdquo in Pro-ceedings of the Canadian Conference on Electrical and ComputerEgineering (CCECE rsquo00) vol 1 pp 340ndash344 May 2000
[5] C Bordas C Dufour and O Rudloff ldquoA 3-level neutral-clamped inverter model with natural switching mode sup-port for the real-time simulation of variable speed drivesrdquoin Proceedings of the International Symposium on AdvancedElectromechanical Motion Systems pp 1ndash8 Lille France 2009
[6] A Myaing and V Dinavahi ldquoFPGA-based real-time emulationof power electronic systems with detailed representation ofdevice characteristicsrdquo IEEE Transactions on Industrial Elec-tronics vol 58 no 1 pp 358ndash368 2011
[7] J H Allmeling and W P Hammer ldquoPLECSmdashpiece-wise linearelectrical circuit simulation for Simulinkrdquo in Proceedings of theIEEE International Conference on Power Electronics and DriveSystems (PEDSrsquo99) vol 1 pp 355ndash360 July 1999
[8] S Venugopal and G Narayanan ldquoDesign of FPGA based digitalplatform for control of power electronics systemsrdquo in Proceed-ings of the National Power Electronics Conference pp 1250ndash1255December 2005
[9] K Jayalakshmi and V Ramanarayanan ldquoReal-time simulationof electrical machines on FPGA platformrdquo in Proceedings of theIndia International Conference on Power Electronics (IICPE rsquo06)pp 259ndash263 Chennai India December 2006
[10] R Krishnan Electric Motor Drives Modeling Analysis andControl Pearson Education Asia 2007
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
Advances in Power Electronics 7
002 004 006 008 01 012 014 016 018 02
0
50
100
150
EMF
phas
e A (V
)DC link two-level (IGBT-diode) inverter
EMF phase A RTDS
minus50
minus100
minus150
Time (s)
Figure 10 Stator ph-A back EMF-REF (blue trace) RTDS (redtrace)
Three-phaseinverter Load
PWM pulses MATLABCode
composerstudio
UncontrolledrectifierAC power
input
DSP1
DSP2
IGBT inverter module-1 IGBT inverter
module-2
RTDS
DSP1
DSP2
UART
DC linkvoltage AC power
output
Figure 11 Block diagram and snapshot of hardware setup
In order to find back emf set 119894119904120572
= 0 and 119894119904120573
= 0 Then119864119904120572
= 119881119904120572 119864119904120573
= 119881119904120573
[119864119904120572
119864119904120573
]
119899
=minus1
(ℎ11 sdot ℎ22 minus ℎ21 sdot ℎ12)[
ℎ22 minusℎ12
minusℎ21 ℎ11]
times [11989213 11989214
11989223 11989224] [
120593119903120572
120593119903120573
]
119899
(19)
ePWM3
WAWB
C280xC28x3xePWM
ePWM2
WAWB
C280xC28x3x
ePWM
ePWM1
WA
WB
C280xC28x3x
ePWM
Sine wave3
Sine wave2
Sine wave1
F28335 eZdsp
Data type conversion2
Uint16
Data type conversion1
Uint16
Data type conversion
Uint16
Figure 12 DSP interface for PWM pulse generation
Table 1 Input parameters for RTDS and Simulink-PLECS
Source parameters DC link inverter Load parametersVm = 1414 lowast 220119891 = 50120596 = 2 lowast pi lowast 119891Rs = 1Ω
Ls = 10mH
Cdc = 10mFFsw = 450Hz119867 = 100119890 minus 6 s
119898 = 08
As given in Table 3
where g119898119899 h119898119899
are the state and input matrix coefficients ofthe stationary reference frame model of induction machineAt every sampling time stator currents have been calculatedusing stator voltages and finally back emf of each phasehas been calculated as per (19) Current sample of back emfhas been used for the next iteration to identify the mode ofoperation of inverter given in Section 3With these equationsa generalized model of the complete electrical drive systemhas been developed and validated with offline Simulink-PLECS model given later
4 Simulation Results
Input parameters for proposedmodel as well as for Simulink-PLECS (REF) offline simulation are shown in Table 1
41 Offline Results versus Real-Time Digital Simulator Inthis case simulations are carried out with both rectifier andinverter now decoupled at DC link Both circuits are treatedas separate circuits and rectifier current with DC link andinverter current with DC link are calculated separately At theend of the iteration DC link voltage will be updated using therectifier and inverter currents
In Figures 4 5 6 7 8 9 and 10 red trace is fromSimulink-PLECS reference results which are overplotted onthat of RTDS-decoupled solution From Figures 4ndash10 it isvery clear that proposed real-timemodel and offline Simulinkresults are matching each other in terms of accuracy as wellas with larger step size of 100120583119904 proposedmodel with the 1120583119904
Simulink reference modelTable 2 shows that at a particular time of sample electrical
and mechanical parameters of real-time electrical drive
8 Advances in Power Electronics
10050
0minus50
minus100018 0185 019 0195 02 0205 021 0215 022 0225
Time (s)
Input phase-phase voltage
Phas
e-ph
ase
volta
ge (V
)
2010
0minus10minus20
Input current (R-phase)
Inpu
t R-p
hase
curr
ent (
A)
018 0185 019 0195 02 0205 021 0215 022 0225Time (s)
(a)
80604020
002 0202 0204 0206 0208 021 0212 0214 0216 0218 022
Time (s)
DC
link
(V)
DC link voltage
201510
50
minus5
DC
link
curr
ent (
A)
02 0202 0204 0206 0208 021 0212 0214 0216 0218 022Time (s)
DC link current
(b)
105
0019 0195 02 0205 021 0215 022 0225 023 0235
Time (s)
Gat
e pul
se (V
) Gate pulses for leg 1
Gate pulses for leg 2
Gate pulses for leg 3
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
Gat
e pul
se (V
)
105
0
105
0
Gat
e pul
se (V
)
(c)
10050
0minus50
minus10002 0205 021 0215 022 0225 023 0235 024 0245
Time (s)
AC output voltagePh
ase-
phas
evo
ltage
(V)
3210
minus1minus2minus3
R-ph
ase c
urre
nt (A
) AC output current (R-phase)
02 0205 021 0215 022 0225 023 0235 024 0245Time (s)
(d)
Figure 13 Proposed mathematical model offline results showing (a) input voltage (ph-ph) and current (R-phase) (b) DC link voltage andcurrent (c) PWM pulses for 3 legs of inverter and (d) output voltage (ph-ph) and current (R-Phase)
Table 2 Comparison of proposed real-time digital simulator results with Simulink-PLECS offline results
S no Parameter Time of sampleReferenceSimulink-PLECS(119886)
Proposed RTDSsolution
(119887)
Percentage of error ()((119887) minus (119886))(119886)
1 DC link voltage V 001 8546 8588 04910102 5001 5009 01
2 Rectifier source current in phase A Amps 0008 1215 1214 minus00820086 2418 2471 219
3 Stator current in phase A Amps 0009512 5195 518 minus000288008951 5596 555 minus000822
4 Inverter line to neutral voltage van (V) 0009512 3333 3333 0008951 3333 3333 0
5 Electromagnetic torque tem (N-m) 001186 6633 6686 0701985 2202 2202 00
6 Rotor speed 120596 (rads) 002 3141 3171 0901922 14848 14851 002
Advances in Power Electronics 9
(a) (b)
(c) (d)
Figure 14 Hardware results from DSP showing (a) input voltage (ph-ph) and current (R-Phase) (b) DC link voltage and current (c) PWMpulses for 3 legs of inverter from DSP and (d) output voltage (ph-ph) and current (R-phase)
systemmodel utilizingAC-DC-AC topology listed previouslyare closelymatchedwith its Simulink reference offline results
5 Real-Time Implementation Using DSP
The given system model is implemented in MATLAB m-file coding and also in real-time hardware setup using theDSP-MATLAB interface PWM are pulses for hardware andMATLAB model generated using DSP processor 2 ePWMmodule is used to generate six pulses at a time from ePWMpins of DSP These pulses are being fed to optocoupler TLP250 which boosts up the voltage level to an extent at whichIGBT switches can be triggered At the same time anotherprocessor is used to run the mathematical model of drivesystem as per decoupled method
Figure 11 represents the block diagram of the hard-ware setup As per specifications given in Appendix A twoSemikron make IGBT IPM module-based inverters used forthis purpose one acts as a rectifier and the other is used as aninverter to drive inductionmotor Pulses fromDSP2 are givento the Semikron inverter module 2 through the optoisolatorICs in order to strengthen the gate drive signal The PWMlogic is developed in Simulink model and Figure 12 showsthe logic generation of bipolar PWM for three-phase inverterComparative results are obtained for the input ph-ph voltageof diode rectifier and input phase current as shown in Figures13(a) and 14(a) Figures 13(b) and 14(b) show DC link voltageand current waveforms
The PWM pulses generated at the output of the optoiso-lator are shown in Figure 14(c) and those from the simulationare shown in Figure 13(c) In Figure 14 all voltage waveformsare phase-phase voltages with the multiplier setting of 200and all current waveforms are phase A current waveforms
with the probe setting at 10mVA Figures 13 and 14(d)reveal that the output voltage between two phases and phasecurrents is closely matched with that of the offline simulationresults As per analytical calculations as well as simulationand hardware results the output RMS voltage obtained acrossthe load is 85V All the parameters are matched except forthe grid voltage and current since it has been assumed as theideal source in simulation model and real grid conditions inthe laboratory are ignored But in practical situations the gridcould be connected to transformers and many other loads inthe laboratory building
6 Conclusion
A new research platform for power electronics and drivesystem modelling using decoupled analytical method hasbeen verified both in offline simulation and in real-timehardware The m-file program developed for state-spacemethod-based electrical drive model accurately matchingwith hardware model The same model has been validatedusing eZdsp processors with one as plant and the other asa controller Decoupled method makes it easier with betteraccuracy and less calculation time which results in fastexecution speed This can be further extended to test thesame with reduced order induction motor model and resultscan be compared with existing results in order to furtherimprovise the real-time model accuracy and its executiontime The results obtained from this work suggest that thedeveloped models using the proposed method can be usedas a research platform and extended to any complex powerelectronic applications The obtained model is flexible andit can be extended to any system with different size (systemorder) These models can be used as user definedfunction
10 Advances in Power Electronics
Table 3 Load specification three-phase induction motor
Parameter Value DescriptionkVAbase 4e3 Rated kVA of the machineVbase 400 Rated voltage (L-L) in (V)Vm 231 lowast radic2 Peak value of AC source voltage (V)119891 50 Rated frequency in Hz120596 2 lowast pi lowast 50 Rated angular frequency in radsRs 1405 Stator resistance in Ω
Ls(Lls + Lm) 0178039 Stator inductance in HRr 1395 Rotor resistance in Ω
Lr(Llr + Lm) 0178039 Rotor inductance in HLm 01722 Stator-rotor mutual inductance in Hℎ 100 Time step in 120583s119899 9 Carrier frequency 119899 times 50Hz119869 00131 Inertia of the machine in kgm2
119861 001841 Friction coefficient in Nmsrad119901 2 No of pole pairs
blocks to test with real-time processorcontroller for futureresearch work
Appendices
A Three-Phase IGBT-Based Inverter(Semikron Make)
IGBT module used SKM75GB123DDC link capacitor 4700 120583FGate driver SKYPER 32 PRO119881dc input 800 (V)119881ac output 415 (V)119868ac output 20 (A)Output frequency 50HzSwitching frequency 10 kHzType of cooling force air cooledTemp 35∘CDuty class class I
B
For more details see Table 3
References
[1] P Livinti and R Pusca ldquoControl of an electric drive system inthe LabVIEWprogramming environmentrdquo inProceedings of the9th International Conference on Remote Engineering and VirtualInstrumentation (REV) pp 1ndash6 Bilbao Spain July 2012
[2] R Champagne L A Dessaint andH Fortin-Blanchette ldquoReal-time simulation of electric drivesrdquoMathematics and Computersin Simulation vol 63 no 3-5 pp 173ndash181 2003
[3] H Eren and C C Fung ldquoVirtual instrumentation of electricdrive systems for automation and testingrdquo in Proceedings ofthe 17th IEEE Instrumentation and Measurement TechnologyConference (IMTC rsquo00) vol 3 pp 1500ndash1505 May 2000
[4] R Champagne L Dessaint G Sybille and B KhodabakhchianldquoApproach for real-time simulation of electric drivesrdquo in Pro-ceedings of the Canadian Conference on Electrical and ComputerEgineering (CCECE rsquo00) vol 1 pp 340ndash344 May 2000
[5] C Bordas C Dufour and O Rudloff ldquoA 3-level neutral-clamped inverter model with natural switching mode sup-port for the real-time simulation of variable speed drivesrdquoin Proceedings of the International Symposium on AdvancedElectromechanical Motion Systems pp 1ndash8 Lille France 2009
[6] A Myaing and V Dinavahi ldquoFPGA-based real-time emulationof power electronic systems with detailed representation ofdevice characteristicsrdquo IEEE Transactions on Industrial Elec-tronics vol 58 no 1 pp 358ndash368 2011
[7] J H Allmeling and W P Hammer ldquoPLECSmdashpiece-wise linearelectrical circuit simulation for Simulinkrdquo in Proceedings of theIEEE International Conference on Power Electronics and DriveSystems (PEDSrsquo99) vol 1 pp 355ndash360 July 1999
[8] S Venugopal and G Narayanan ldquoDesign of FPGA based digitalplatform for control of power electronics systemsrdquo in Proceed-ings of the National Power Electronics Conference pp 1250ndash1255December 2005
[9] K Jayalakshmi and V Ramanarayanan ldquoReal-time simulationof electrical machines on FPGA platformrdquo in Proceedings of theIndia International Conference on Power Electronics (IICPE rsquo06)pp 259ndash263 Chennai India December 2006
[10] R Krishnan Electric Motor Drives Modeling Analysis andControl Pearson Education Asia 2007
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
8 Advances in Power Electronics
10050
0minus50
minus100018 0185 019 0195 02 0205 021 0215 022 0225
Time (s)
Input phase-phase voltage
Phas
e-ph
ase
volta
ge (V
)
2010
0minus10minus20
Input current (R-phase)
Inpu
t R-p
hase
curr
ent (
A)
018 0185 019 0195 02 0205 021 0215 022 0225Time (s)
(a)
80604020
002 0202 0204 0206 0208 021 0212 0214 0216 0218 022
Time (s)
DC
link
(V)
DC link voltage
201510
50
minus5
DC
link
curr
ent (
A)
02 0202 0204 0206 0208 021 0212 0214 0216 0218 022Time (s)
DC link current
(b)
105
0019 0195 02 0205 021 0215 022 0225 023 0235
Time (s)
Gat
e pul
se (V
) Gate pulses for leg 1
Gate pulses for leg 2
Gate pulses for leg 3
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
019 0195 02 0205 021 0215 022 0225 023 0235Time (s)
Gat
e pul
se (V
)
105
0
105
0
Gat
e pul
se (V
)
(c)
10050
0minus50
minus10002 0205 021 0215 022 0225 023 0235 024 0245
Time (s)
AC output voltagePh
ase-
phas
evo
ltage
(V)
3210
minus1minus2minus3
R-ph
ase c
urre
nt (A
) AC output current (R-phase)
02 0205 021 0215 022 0225 023 0235 024 0245Time (s)
(d)
Figure 13 Proposed mathematical model offline results showing (a) input voltage (ph-ph) and current (R-phase) (b) DC link voltage andcurrent (c) PWM pulses for 3 legs of inverter and (d) output voltage (ph-ph) and current (R-Phase)
Table 2 Comparison of proposed real-time digital simulator results with Simulink-PLECS offline results
S no Parameter Time of sampleReferenceSimulink-PLECS(119886)
Proposed RTDSsolution
(119887)
Percentage of error ()((119887) minus (119886))(119886)
1 DC link voltage V 001 8546 8588 04910102 5001 5009 01
2 Rectifier source current in phase A Amps 0008 1215 1214 minus00820086 2418 2471 219
3 Stator current in phase A Amps 0009512 5195 518 minus000288008951 5596 555 minus000822
4 Inverter line to neutral voltage van (V) 0009512 3333 3333 0008951 3333 3333 0
5 Electromagnetic torque tem (N-m) 001186 6633 6686 0701985 2202 2202 00
6 Rotor speed 120596 (rads) 002 3141 3171 0901922 14848 14851 002
Advances in Power Electronics 9
(a) (b)
(c) (d)
Figure 14 Hardware results from DSP showing (a) input voltage (ph-ph) and current (R-Phase) (b) DC link voltage and current (c) PWMpulses for 3 legs of inverter from DSP and (d) output voltage (ph-ph) and current (R-phase)
systemmodel utilizingAC-DC-AC topology listed previouslyare closelymatchedwith its Simulink reference offline results
5 Real-Time Implementation Using DSP
The given system model is implemented in MATLAB m-file coding and also in real-time hardware setup using theDSP-MATLAB interface PWM are pulses for hardware andMATLAB model generated using DSP processor 2 ePWMmodule is used to generate six pulses at a time from ePWMpins of DSP These pulses are being fed to optocoupler TLP250 which boosts up the voltage level to an extent at whichIGBT switches can be triggered At the same time anotherprocessor is used to run the mathematical model of drivesystem as per decoupled method
Figure 11 represents the block diagram of the hard-ware setup As per specifications given in Appendix A twoSemikron make IGBT IPM module-based inverters used forthis purpose one acts as a rectifier and the other is used as aninverter to drive inductionmotor Pulses fromDSP2 are givento the Semikron inverter module 2 through the optoisolatorICs in order to strengthen the gate drive signal The PWMlogic is developed in Simulink model and Figure 12 showsthe logic generation of bipolar PWM for three-phase inverterComparative results are obtained for the input ph-ph voltageof diode rectifier and input phase current as shown in Figures13(a) and 14(a) Figures 13(b) and 14(b) show DC link voltageand current waveforms
The PWM pulses generated at the output of the optoiso-lator are shown in Figure 14(c) and those from the simulationare shown in Figure 13(c) In Figure 14 all voltage waveformsare phase-phase voltages with the multiplier setting of 200and all current waveforms are phase A current waveforms
with the probe setting at 10mVA Figures 13 and 14(d)reveal that the output voltage between two phases and phasecurrents is closely matched with that of the offline simulationresults As per analytical calculations as well as simulationand hardware results the output RMS voltage obtained acrossthe load is 85V All the parameters are matched except forthe grid voltage and current since it has been assumed as theideal source in simulation model and real grid conditions inthe laboratory are ignored But in practical situations the gridcould be connected to transformers and many other loads inthe laboratory building
6 Conclusion
A new research platform for power electronics and drivesystem modelling using decoupled analytical method hasbeen verified both in offline simulation and in real-timehardware The m-file program developed for state-spacemethod-based electrical drive model accurately matchingwith hardware model The same model has been validatedusing eZdsp processors with one as plant and the other asa controller Decoupled method makes it easier with betteraccuracy and less calculation time which results in fastexecution speed This can be further extended to test thesame with reduced order induction motor model and resultscan be compared with existing results in order to furtherimprovise the real-time model accuracy and its executiontime The results obtained from this work suggest that thedeveloped models using the proposed method can be usedas a research platform and extended to any complex powerelectronic applications The obtained model is flexible andit can be extended to any system with different size (systemorder) These models can be used as user definedfunction
10 Advances in Power Electronics
Table 3 Load specification three-phase induction motor
Parameter Value DescriptionkVAbase 4e3 Rated kVA of the machineVbase 400 Rated voltage (L-L) in (V)Vm 231 lowast radic2 Peak value of AC source voltage (V)119891 50 Rated frequency in Hz120596 2 lowast pi lowast 50 Rated angular frequency in radsRs 1405 Stator resistance in Ω
Ls(Lls + Lm) 0178039 Stator inductance in HRr 1395 Rotor resistance in Ω
Lr(Llr + Lm) 0178039 Rotor inductance in HLm 01722 Stator-rotor mutual inductance in Hℎ 100 Time step in 120583s119899 9 Carrier frequency 119899 times 50Hz119869 00131 Inertia of the machine in kgm2
119861 001841 Friction coefficient in Nmsrad119901 2 No of pole pairs
blocks to test with real-time processorcontroller for futureresearch work
Appendices
A Three-Phase IGBT-Based Inverter(Semikron Make)
IGBT module used SKM75GB123DDC link capacitor 4700 120583FGate driver SKYPER 32 PRO119881dc input 800 (V)119881ac output 415 (V)119868ac output 20 (A)Output frequency 50HzSwitching frequency 10 kHzType of cooling force air cooledTemp 35∘CDuty class class I
B
For more details see Table 3
References
[1] P Livinti and R Pusca ldquoControl of an electric drive system inthe LabVIEWprogramming environmentrdquo inProceedings of the9th International Conference on Remote Engineering and VirtualInstrumentation (REV) pp 1ndash6 Bilbao Spain July 2012
[2] R Champagne L A Dessaint andH Fortin-Blanchette ldquoReal-time simulation of electric drivesrdquoMathematics and Computersin Simulation vol 63 no 3-5 pp 173ndash181 2003
[3] H Eren and C C Fung ldquoVirtual instrumentation of electricdrive systems for automation and testingrdquo in Proceedings ofthe 17th IEEE Instrumentation and Measurement TechnologyConference (IMTC rsquo00) vol 3 pp 1500ndash1505 May 2000
[4] R Champagne L Dessaint G Sybille and B KhodabakhchianldquoApproach for real-time simulation of electric drivesrdquo in Pro-ceedings of the Canadian Conference on Electrical and ComputerEgineering (CCECE rsquo00) vol 1 pp 340ndash344 May 2000
[5] C Bordas C Dufour and O Rudloff ldquoA 3-level neutral-clamped inverter model with natural switching mode sup-port for the real-time simulation of variable speed drivesrdquoin Proceedings of the International Symposium on AdvancedElectromechanical Motion Systems pp 1ndash8 Lille France 2009
[6] A Myaing and V Dinavahi ldquoFPGA-based real-time emulationof power electronic systems with detailed representation ofdevice characteristicsrdquo IEEE Transactions on Industrial Elec-tronics vol 58 no 1 pp 358ndash368 2011
[7] J H Allmeling and W P Hammer ldquoPLECSmdashpiece-wise linearelectrical circuit simulation for Simulinkrdquo in Proceedings of theIEEE International Conference on Power Electronics and DriveSystems (PEDSrsquo99) vol 1 pp 355ndash360 July 1999
[8] S Venugopal and G Narayanan ldquoDesign of FPGA based digitalplatform for control of power electronics systemsrdquo in Proceed-ings of the National Power Electronics Conference pp 1250ndash1255December 2005
[9] K Jayalakshmi and V Ramanarayanan ldquoReal-time simulationof electrical machines on FPGA platformrdquo in Proceedings of theIndia International Conference on Power Electronics (IICPE rsquo06)pp 259ndash263 Chennai India December 2006
[10] R Krishnan Electric Motor Drives Modeling Analysis andControl Pearson Education Asia 2007
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
Advances in Power Electronics 9
(a) (b)
(c) (d)
Figure 14 Hardware results from DSP showing (a) input voltage (ph-ph) and current (R-Phase) (b) DC link voltage and current (c) PWMpulses for 3 legs of inverter from DSP and (d) output voltage (ph-ph) and current (R-phase)
systemmodel utilizingAC-DC-AC topology listed previouslyare closelymatchedwith its Simulink reference offline results
5 Real-Time Implementation Using DSP
The given system model is implemented in MATLAB m-file coding and also in real-time hardware setup using theDSP-MATLAB interface PWM are pulses for hardware andMATLAB model generated using DSP processor 2 ePWMmodule is used to generate six pulses at a time from ePWMpins of DSP These pulses are being fed to optocoupler TLP250 which boosts up the voltage level to an extent at whichIGBT switches can be triggered At the same time anotherprocessor is used to run the mathematical model of drivesystem as per decoupled method
Figure 11 represents the block diagram of the hard-ware setup As per specifications given in Appendix A twoSemikron make IGBT IPM module-based inverters used forthis purpose one acts as a rectifier and the other is used as aninverter to drive inductionmotor Pulses fromDSP2 are givento the Semikron inverter module 2 through the optoisolatorICs in order to strengthen the gate drive signal The PWMlogic is developed in Simulink model and Figure 12 showsthe logic generation of bipolar PWM for three-phase inverterComparative results are obtained for the input ph-ph voltageof diode rectifier and input phase current as shown in Figures13(a) and 14(a) Figures 13(b) and 14(b) show DC link voltageand current waveforms
The PWM pulses generated at the output of the optoiso-lator are shown in Figure 14(c) and those from the simulationare shown in Figure 13(c) In Figure 14 all voltage waveformsare phase-phase voltages with the multiplier setting of 200and all current waveforms are phase A current waveforms
with the probe setting at 10mVA Figures 13 and 14(d)reveal that the output voltage between two phases and phasecurrents is closely matched with that of the offline simulationresults As per analytical calculations as well as simulationand hardware results the output RMS voltage obtained acrossthe load is 85V All the parameters are matched except forthe grid voltage and current since it has been assumed as theideal source in simulation model and real grid conditions inthe laboratory are ignored But in practical situations the gridcould be connected to transformers and many other loads inthe laboratory building
6 Conclusion
A new research platform for power electronics and drivesystem modelling using decoupled analytical method hasbeen verified both in offline simulation and in real-timehardware The m-file program developed for state-spacemethod-based electrical drive model accurately matchingwith hardware model The same model has been validatedusing eZdsp processors with one as plant and the other asa controller Decoupled method makes it easier with betteraccuracy and less calculation time which results in fastexecution speed This can be further extended to test thesame with reduced order induction motor model and resultscan be compared with existing results in order to furtherimprovise the real-time model accuracy and its executiontime The results obtained from this work suggest that thedeveloped models using the proposed method can be usedas a research platform and extended to any complex powerelectronic applications The obtained model is flexible andit can be extended to any system with different size (systemorder) These models can be used as user definedfunction
10 Advances in Power Electronics
Table 3 Load specification three-phase induction motor
Parameter Value DescriptionkVAbase 4e3 Rated kVA of the machineVbase 400 Rated voltage (L-L) in (V)Vm 231 lowast radic2 Peak value of AC source voltage (V)119891 50 Rated frequency in Hz120596 2 lowast pi lowast 50 Rated angular frequency in radsRs 1405 Stator resistance in Ω
Ls(Lls + Lm) 0178039 Stator inductance in HRr 1395 Rotor resistance in Ω
Lr(Llr + Lm) 0178039 Rotor inductance in HLm 01722 Stator-rotor mutual inductance in Hℎ 100 Time step in 120583s119899 9 Carrier frequency 119899 times 50Hz119869 00131 Inertia of the machine in kgm2
119861 001841 Friction coefficient in Nmsrad119901 2 No of pole pairs
blocks to test with real-time processorcontroller for futureresearch work
Appendices
A Three-Phase IGBT-Based Inverter(Semikron Make)
IGBT module used SKM75GB123DDC link capacitor 4700 120583FGate driver SKYPER 32 PRO119881dc input 800 (V)119881ac output 415 (V)119868ac output 20 (A)Output frequency 50HzSwitching frequency 10 kHzType of cooling force air cooledTemp 35∘CDuty class class I
B
For more details see Table 3
References
[1] P Livinti and R Pusca ldquoControl of an electric drive system inthe LabVIEWprogramming environmentrdquo inProceedings of the9th International Conference on Remote Engineering and VirtualInstrumentation (REV) pp 1ndash6 Bilbao Spain July 2012
[2] R Champagne L A Dessaint andH Fortin-Blanchette ldquoReal-time simulation of electric drivesrdquoMathematics and Computersin Simulation vol 63 no 3-5 pp 173ndash181 2003
[3] H Eren and C C Fung ldquoVirtual instrumentation of electricdrive systems for automation and testingrdquo in Proceedings ofthe 17th IEEE Instrumentation and Measurement TechnologyConference (IMTC rsquo00) vol 3 pp 1500ndash1505 May 2000
[4] R Champagne L Dessaint G Sybille and B KhodabakhchianldquoApproach for real-time simulation of electric drivesrdquo in Pro-ceedings of the Canadian Conference on Electrical and ComputerEgineering (CCECE rsquo00) vol 1 pp 340ndash344 May 2000
[5] C Bordas C Dufour and O Rudloff ldquoA 3-level neutral-clamped inverter model with natural switching mode sup-port for the real-time simulation of variable speed drivesrdquoin Proceedings of the International Symposium on AdvancedElectromechanical Motion Systems pp 1ndash8 Lille France 2009
[6] A Myaing and V Dinavahi ldquoFPGA-based real-time emulationof power electronic systems with detailed representation ofdevice characteristicsrdquo IEEE Transactions on Industrial Elec-tronics vol 58 no 1 pp 358ndash368 2011
[7] J H Allmeling and W P Hammer ldquoPLECSmdashpiece-wise linearelectrical circuit simulation for Simulinkrdquo in Proceedings of theIEEE International Conference on Power Electronics and DriveSystems (PEDSrsquo99) vol 1 pp 355ndash360 July 1999
[8] S Venugopal and G Narayanan ldquoDesign of FPGA based digitalplatform for control of power electronics systemsrdquo in Proceed-ings of the National Power Electronics Conference pp 1250ndash1255December 2005
[9] K Jayalakshmi and V Ramanarayanan ldquoReal-time simulationof electrical machines on FPGA platformrdquo in Proceedings of theIndia International Conference on Power Electronics (IICPE rsquo06)pp 259ndash263 Chennai India December 2006
[10] R Krishnan Electric Motor Drives Modeling Analysis andControl Pearson Education Asia 2007
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
10 Advances in Power Electronics
Table 3 Load specification three-phase induction motor
Parameter Value DescriptionkVAbase 4e3 Rated kVA of the machineVbase 400 Rated voltage (L-L) in (V)Vm 231 lowast radic2 Peak value of AC source voltage (V)119891 50 Rated frequency in Hz120596 2 lowast pi lowast 50 Rated angular frequency in radsRs 1405 Stator resistance in Ω
Ls(Lls + Lm) 0178039 Stator inductance in HRr 1395 Rotor resistance in Ω
Lr(Llr + Lm) 0178039 Rotor inductance in HLm 01722 Stator-rotor mutual inductance in Hℎ 100 Time step in 120583s119899 9 Carrier frequency 119899 times 50Hz119869 00131 Inertia of the machine in kgm2
119861 001841 Friction coefficient in Nmsrad119901 2 No of pole pairs
blocks to test with real-time processorcontroller for futureresearch work
Appendices
A Three-Phase IGBT-Based Inverter(Semikron Make)
IGBT module used SKM75GB123DDC link capacitor 4700 120583FGate driver SKYPER 32 PRO119881dc input 800 (V)119881ac output 415 (V)119868ac output 20 (A)Output frequency 50HzSwitching frequency 10 kHzType of cooling force air cooledTemp 35∘CDuty class class I
B
For more details see Table 3
References
[1] P Livinti and R Pusca ldquoControl of an electric drive system inthe LabVIEWprogramming environmentrdquo inProceedings of the9th International Conference on Remote Engineering and VirtualInstrumentation (REV) pp 1ndash6 Bilbao Spain July 2012
[2] R Champagne L A Dessaint andH Fortin-Blanchette ldquoReal-time simulation of electric drivesrdquoMathematics and Computersin Simulation vol 63 no 3-5 pp 173ndash181 2003
[3] H Eren and C C Fung ldquoVirtual instrumentation of electricdrive systems for automation and testingrdquo in Proceedings ofthe 17th IEEE Instrumentation and Measurement TechnologyConference (IMTC rsquo00) vol 3 pp 1500ndash1505 May 2000
[4] R Champagne L Dessaint G Sybille and B KhodabakhchianldquoApproach for real-time simulation of electric drivesrdquo in Pro-ceedings of the Canadian Conference on Electrical and ComputerEgineering (CCECE rsquo00) vol 1 pp 340ndash344 May 2000
[5] C Bordas C Dufour and O Rudloff ldquoA 3-level neutral-clamped inverter model with natural switching mode sup-port for the real-time simulation of variable speed drivesrdquoin Proceedings of the International Symposium on AdvancedElectromechanical Motion Systems pp 1ndash8 Lille France 2009
[6] A Myaing and V Dinavahi ldquoFPGA-based real-time emulationof power electronic systems with detailed representation ofdevice characteristicsrdquo IEEE Transactions on Industrial Elec-tronics vol 58 no 1 pp 358ndash368 2011
[7] J H Allmeling and W P Hammer ldquoPLECSmdashpiece-wise linearelectrical circuit simulation for Simulinkrdquo in Proceedings of theIEEE International Conference on Power Electronics and DriveSystems (PEDSrsquo99) vol 1 pp 355ndash360 July 1999
[8] S Venugopal and G Narayanan ldquoDesign of FPGA based digitalplatform for control of power electronics systemsrdquo in Proceed-ings of the National Power Electronics Conference pp 1250ndash1255December 2005
[9] K Jayalakshmi and V Ramanarayanan ldquoReal-time simulationof electrical machines on FPGA platformrdquo in Proceedings of theIndia International Conference on Power Electronics (IICPE rsquo06)pp 259ndash263 Chennai India December 2006
[10] R Krishnan Electric Motor Drives Modeling Analysis andControl Pearson Education Asia 2007
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of
International Journal of
AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
RoboticsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Active and Passive Electronic Components
Control Scienceand Engineering
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
International Journal of
RotatingMachinery
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporation httpwwwhindawicom
Journal ofEngineeringVolume 2014
Submit your manuscripts athttpwwwhindawicom
VLSI Design
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Shock and Vibration
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Civil EngineeringAdvances in
Acoustics and VibrationAdvances in
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Electrical and Computer Engineering
Journal of
Advances inOptoElectronics
Hindawi Publishing Corporation httpwwwhindawicom
Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
SensorsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chemical EngineeringInternational Journal of Antennas and
Propagation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Navigation and Observation
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
DistributedSensor Networks
International Journal of